{"gene":"GCC2","run_date":"2026-06-10T01:55:21","timeline":{"discoveries":[{"year":2002,"finding":"GCC185 (GCC2) is a peripheral membrane protein with a C-terminal GRIP domain that targets it to the trans-Golgi network (TGN); the GRIP domain is necessary and sufficient for TGN targeting, and GCC185 localizes to a TGN subcompartment distinct from alpha2,6-sialyltransferase and cis-Golgi markers.","method":"Immunofluorescence, immunoelectron microscopy, overexpression of full-length and truncated constructs in HeLa cells","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 2 / Strong — direct localization experiment with domain mapping, replicated across multiple constructs and imaging modalities, foundational characterization paper","pmids":["12446665"],"is_preprint":false},{"year":2006,"finding":"GCC185 (GCC2) is a Rab9 effector required for mannose 6-phosphate receptor (MPR) recycling from late endosomes to the TGN; depletion of GCC185 triggers enhanced MPR degradation and elevated secretion of hexosaminidase, and GCC185 functions in MPR recycling both in living cells and in vitro.","method":"siRNA depletion, in vitro transport assay, functional rescue, hexosaminidase secretion assay","journal":"Molecular biology of the cell","confidence":"High","confidence_rationale":"Tier 2 / Strong — multiple orthogonal functional assays (in vitro and in vivo), siRNA depletion with specific phenotypic readouts, replicated in subsequent studies","pmids":["16885419"],"is_preprint":false},{"year":2007,"finding":"GCC185 (GCC2) is essential for endosome-to-TGN transport of shiga toxin (which accumulates in Rab11-positive recycling endosomes upon GCC185 depletion) and for maintaining Golgi ribbon organization; depletion causes Golgi fragmentation with dispersal of both cis and trans markers, while TGN38 recycling and anterograde E-cadherin transport are initially unaffected.","method":"siRNA and miRNA depletion in HeLa cells, shiga toxin trafficking assay, mannose-6-phosphate receptor distribution, immunofluorescence","journal":"Traffic (Copenhagen, Denmark)","confidence":"High","confidence_rationale":"Tier 2 / Strong — two independent knockdown methods (siRNA and miRNA), multiple cargo readouts, replicated findings consistent with prior work","pmids":["17488291"],"is_preprint":false},{"year":2008,"finding":"GCC185 (GCC2) is recruited to the Golgi by cooperative interaction with two small GTPases: Rab6 binds a coiled-coil domain immediately adjacent to the C-terminal GRIP domain, and Rab6 binding promotes association of Arl1 with the GRIP domain; crystal structure of Rab6 bound to the GCC185 Rab-binding domain reveals Rab6 recognizes a two-fold symmetric surface on the coiled coil.","method":"Crystal structure determination, mutagenesis of Rab-binding residues, Golgi localization assay, in vitro binding assays","journal":"Cell","confidence":"High","confidence_rationale":"Tier 1 / Moderate — crystal structure plus mutagenesis plus localization assay in a single study; however, contradicted by a subsequent study (PMID:19703403)","pmids":["18243103"],"is_preprint":false},{"year":2008,"finding":"GCC185 (GCC2) contains at least four additional Rab GTPase binding sites distributed across its length that can bind up to 14 different Rab GTPases; a central coiled-coil domain contains a specific Rab9 binding site that is functionally important for MPR recycling to the Golgi.","method":"Yeast two-hybrid, direct biochemical binding assays, siRNA depletion with plasmid rescue, functional MPR recycling assay","journal":"Molecular biology of the cell","confidence":"High","confidence_rationale":"Tier 2 / Strong — yeast two-hybrid combined with direct biochemical tests and functional rescue assays, multiple Rab binding sites mapped across the protein","pmids":["18946081"],"is_preprint":false},{"year":2009,"finding":"Endogenous GCC185 (GCC2) Golgi localization does not require Rab6A/A' or Arl1; depletion of both Rab6A/A' and Arl1 had no effect on localization of endogenous GCC185 or its isolated GRIP domain, and minimal colocalization between Rab6A/A' and endogenous GCC185 was detected on Golgi membranes.","method":"Rab6A/A' and Arl1 depletion (siRNA), yeast two-hybrid (negative result for Rab6A/A' interaction with GCC185 C-terminal domain), immunofluorescence colocalization","journal":"Cell","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — negative result contradicting PMID:18243103, using endogenous protein and two orthogonal methods; single lab, contradicts prior crystal structure-based model","pmids":["19703403"],"is_preprint":false},{"year":2011,"finding":"GCC185 (GCC2) contains two functionally distinct domains: one required for Golgi structure maintenance and a separate domain required for vesicle tethering that directly binds the clathrin adaptor AP-1; cells depleted of GCC185 accumulate MPRs in AP-1-decorated transport vesicles, indicating GCC185 tethers AP-1-coated vesicles carrying MPRs from late endosomes to the TGN.","method":"Domain deletion/rescue experiments, co-immunoprecipitation of AP-1, siRNA depletion with vesicle accumulation assay, immunofluorescence","journal":"The Journal of cell biology","confidence":"High","confidence_rationale":"Tier 2 / Strong — domain dissection with functional rescue, AP-1 interaction identified by co-IP, vesicle accumulation phenotype providing mechanistic insight into two independent functions","pmids":["21875948"],"is_preprint":false},{"year":2011,"finding":"ARL4A directly interacts with GCC185 (GCC2) in a GTP-dependent manner via the CC2 coiled-coil sub-domain of GCC185; this interaction is required for GCC185 to recruit CLASP1 and CLASP2 to the Golgi, which is necessary for Golgi structure maintenance. Depletion of ARL4A impairs GCC185–CLASP interaction and phenocopies GCC185 depletion (Golgi fragmentation, endosome-to-Golgi transport defects).","method":"Co-immunoprecipitation, GST pulldown, siRNA depletion of ARL4A, domain deletion mapping, CLASP recruitment assay","journal":"Journal of cell science","confidence":"High","confidence_rationale":"Tier 2 / Strong — reciprocal co-IP, domain mapping, functional phenocopy by ARL4A depletion, CLASP recruitment assay provide multiple orthogonal lines of evidence","pmids":["22159419"],"is_preprint":false},{"year":2016,"finding":"HIV-1 Nef binds to GCC185 (GCC2) via the N-terminal EEEE65 acidic domain of Nef; this interaction disrupts GCC185–Rab9 interaction, causing delocalization of CI-MPR and elevated hexosaminidase secretion, thereby disrupting retrograde vesicular transport from late endosomes to the TGN.","method":"Co-immunoprecipitation, C. elegans screen followed by biochemical characterization, hexosaminidase secretion assay, CI-MPR localization assay","journal":"Biochemical and biophysical research communications","confidence":"Medium","confidence_rationale":"Tier 3 / Weak — single lab, co-IP-based interaction mapping with functional readout, but limited orthogonal validation","pmids":["27105913"],"is_preprint":false},{"year":2017,"finding":"The GCC2-ALK fusion protein acts as a constitutively activated oncogenic kinase: it promotes IL-3-independent growth of Ba/F3 cells and leads to hyper-activation of ALK downstream signaling (MAPK, PI3K, STAT3 pathways) in HEK-293 and 293T cells; this activation is inhibited by crizotinib.","method":"Ba/F3 cell proliferation assay (IL-3 independence), ectopic expression in HEK-293/293T cells, western blot for downstream signaling, crizotinib inhibition assay","journal":"Lung cancer (Amsterdam, Netherlands)","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — cell-based functional assays with signaling pathway readouts in two cell systems, single lab","pmids":["29290262"],"is_preprint":false},{"year":2019,"finding":"HIV-1 Nef assembles a multi-protein complex at the TGN through GCC185 (GCC2) as a focal scaffold; GCC185-dependent complex includes MHC-I and SFK, while Nef-dependent components include AP-1 and PI3K; siRNA knockdown of GCC185 in Jurkat T cells causes MHC-I accumulation at GCC185, linking GCC185 to Nef-mediated MHC-I downregulation.","method":"Co-immunoprecipitation in Jurkat T and THP-1 cells, siRNA knockdown of GCC185, confocal microscopy, flow cytometry for MHC-I surface levels","journal":"Life sciences","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — multiple co-IPs with different antibodies and cell types, siRNA knockdown phenotype, but single lab and relatively limited mechanistic dissection","pmids":["30953643"],"is_preprint":false},{"year":2024,"finding":"GCC2 knockdown in NSCLC cells decreases EGFR expression and suppresses downstream growth/proliferation signaling, while also compromising Golgi structural integrity and reducing exosome secretion; these results indicate GCC2 regulates EGFR signaling and intracellular trafficking in cancer cells.","method":"shRNA-mediated GCC2 knockdown, western blot for EGFR and downstream signaling, cell proliferation/migration/EMT assays, Golgi morphology imaging, exosome secretion assay, in vivo xenograft","journal":"Scientific reports","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — shRNA knockdown with multiple phenotypic readouts and in vivo validation, but mechanistic link between GCC2 and EGFR regulation is not molecularly dissected","pmids":["39572606"],"is_preprint":false}],"current_model":"GCC2 (GCC185) is a large coiled-coil tethering protein of the trans-Golgi network that is recruited to the Golgi via its C-terminal GRIP domain and interactions with small GTPases (including ARL4A), where it performs at least two independent functions: (1) tethering of AP-1-decorated, Rab9-bearing transport vesicles carrying mannose 6-phosphate receptors from late endosomes to the TGN, and (2) maintaining Golgi ribbon integrity by recruiting CLASP1/2 microtubule-associated proteins through an ARL4A-dependent mechanism; additionally, GCC2 can be co-opted by HIV-1 Nef as a scaffold for multi-protein complex assembly that mediates MHC-I downregulation, and GCC2 chromosomal rearrangements create constitutively active GCC2-ALK and GCC2-PDGFRB oncogenic fusion kinases."},"narrative":{"mechanistic_narrative":"GCC2 (GCC185) is a peripheral membrane coiled-coil tethering protein of the trans-Golgi network (TGN) that coordinates retrograde vesicle capture and Golgi ribbon architecture [PMID:12446665, PMID:21875948]. Its C-terminal GRIP domain is necessary and sufficient for targeting to a distinct TGN subcompartment [PMID:12446665], and the protein is recruited and oriented through interactions with small GTPases, binding up to 14 Rab GTPases across multiple sites along its length, including a functionally critical central Rab9-binding site [PMID:18946081]. Through this Rab9-effector activity GCC2 mediates recycling of mannose 6-phosphate receptors (MPRs) from late endosomes to the TGN, such that its depletion drives MPR mis-sorting, enhanced MPR degradation, and elevated lysosomal hydrolase secretion [PMID:16885419]; the same retrograde route delivers shiga toxin to the Golgi [PMID:17488291]. GCC2 separates these activities into discrete domains: a vesicle-tethering domain that directly binds the clathrin adaptor AP-1 to capture MPR-laden, AP-1-decorated transport vesicles, and a separate domain dedicated to maintaining Golgi structure [PMID:21875948]. Golgi ribbon integrity is sustained through a GTP-dependent interaction with ARL4A via the CC2 coiled-coil sub-domain, which licenses GCC2 to recruit the microtubule-associated proteins CLASP1 and CLASP2 to the Golgi [PMID:22159419]. GCC2 is co-opted in disease contexts: HIV-1 Nef binds GCC2 to disrupt the GCC2–Rab9 interaction and impair retrograde transport [PMID:27105913], and uses GCC2 as a focal scaffold to assemble a multi-protein complex driving MHC-I downregulation [PMID:30953643]; chromosomal rearrangement generates a constitutively active GCC2-ALK oncogenic fusion kinase that hyperactivates MAPK, PI3K, and STAT3 signaling and is sensitive to crizotinib [PMID:29290262].","teleology":[{"year":2002,"claim":"Established where GCC2 acts in the cell and how it is targeted there, defining it as a GRIP-domain TGN protein occupying a distinct subcompartment.","evidence":"Immunofluorescence, immunoelectron microscopy, and truncation constructs in HeLa cells","pmids":["12446665"],"confidence":"High","gaps":["Did not identify the GTPase or lipid partners mediating GRIP-domain recruitment","No functional role assigned"]},{"year":2006,"claim":"Assigned GCC2 a concrete transport function by showing it is a Rab9 effector required for MPR recycling from late endosomes to the TGN.","evidence":"siRNA depletion, in vitro transport assay, functional rescue, hexosaminidase secretion assay","pmids":["16885419"],"confidence":"High","gaps":["Molecular mechanism of vesicle capture not resolved","Did not distinguish tethering from sorting roles"]},{"year":2007,"claim":"Broadened GCC2 function to general retrograde endosome-to-TGN transport and revealed a second, separable role in Golgi ribbon organization.","evidence":"siRNA and miRNA depletion in HeLa cells, shiga toxin trafficking and MPR distribution assays","pmids":["17488291"],"confidence":"High","gaps":["Did not determine whether transport and structural defects share a mechanism","Cargo selectivity of the retrograde pathway unexplained"]},{"year":2008,"claim":"Mapped the GTPase code recruiting and orienting GCC2, identifying Rab6/Arl1 cooperative recruitment at the C-terminus and a dispersed set of Rab-binding sites including a functional Rab9 site.","evidence":"Crystal structure of Rab6–GCC2 RBD, mutagenesis, yeast two-hybrid, biochemical binding, and functional rescue assays","pmids":["18243103","18946081"],"confidence":"High","gaps":["The Rab6/Arl1 recruitment model was contradicted for endogenous protein","Functional significance of most of the 14 Rab interactions undefined"]},{"year":2009,"claim":"Challenged the Rab6/Arl1 recruitment model by showing endogenous GCC2 Golgi localization is independent of Rab6A/A' and Arl1.","evidence":"Rab6A/A' and Arl1 siRNA depletion, yeast two-hybrid, and colocalization on endogenous protein","pmids":["19703403"],"confidence":"Medium","gaps":["Negative result from a single lab contradicting prior crystal structure work","Did not identify the alternative endogenous recruitment determinant"]},{"year":2011,"claim":"Resolved GCC2 into two molecularly distinct activities and identified the direct tethering partner, showing one domain binds AP-1 to capture MPR-laden vesicles while a separate domain maintains Golgi structure.","evidence":"Domain deletion/rescue, AP-1 co-IP, siRNA with vesicle accumulation assay; and ARL4A GTP-dependent co-IP/GST pulldown with CLASP recruitment assay","pmids":["21875948","22159419"],"confidence":"High","gaps":["How CLASP recruitment maintains ribbon integrity mechanistically unresolved","Coupling between AP-1 tethering and Rab9/MPR sorting not detailed"]},{"year":2019,"claim":"Showed GCC2 is exploited as a viral scaffold, with HIV-1 Nef binding GCC2 to disrupt Rab9 association and assemble a TGN complex driving MHC-I downregulation.","evidence":"Co-IP in Jurkat T and THP-1 cells, siRNA knockdown, confocal microscopy, hexosaminidase and MHC-I flow cytometry","pmids":["27105913","30953643"],"confidence":"Medium","gaps":["Single-lab interaction mapping with limited orthogonal validation","Stoichiometry and architecture of the Nef-GCC2 complex undefined"]},{"year":2024,"claim":"Linked GCC2 to cancer cell biology, both as a constitutively active fusion kinase (GCC2-ALK) and as a regulator of EGFR signaling and trafficking when its levels are altered.","evidence":"Ba/F3 IL-3 independence and crizotinib assays for GCC2-ALK; shRNA knockdown with EGFR/signaling readouts, Golgi imaging, exosome and xenograft assays for NSCLC","pmids":["29290262","39572606"],"confidence":"Medium","gaps":["Molecular link between GCC2 and EGFR regulation not dissected","Whether EGFR effects are secondary to Golgi/trafficking disruption unclear"]},{"year":null,"claim":"The endogenous determinant of GCC2 Golgi recruitment and the mechanism coupling its tethering, GTPase-binding, and structural roles remain unresolved.","evidence":"","pmids":[],"confidence":"Medium","gaps":["Reconciliation of the Rab6/Arl1 crystal model with the negative endogenous-depletion result is unsettled","No unified mechanism connecting CLASP-dependent ribbon maintenance to vesicle tethering"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0060090","term_label":"molecular adaptor activity","supporting_discovery_ids":[6]},{"term_id":"GO:0008092","term_label":"cytoskeletal protein binding","supporting_discovery_ids":[7]},{"term_id":"GO:0098772","term_label":"molecular function regulator activity","supporting_discovery_ids":[3,4]}],"localization":[{"term_id":"GO:0005794","term_label":"Golgi apparatus","supporting_discovery_ids":[0,2]}],"pathway":[{"term_id":"R-HSA-5653656","term_label":"Vesicle-mediated transport","supporting_discovery_ids":[1,2,6]},{"term_id":"R-HSA-9609507","term_label":"Protein localization","supporting_discovery_ids":[1,6]},{"term_id":"R-HSA-1852241","term_label":"Organelle biogenesis and maintenance","supporting_discovery_ids":[2,7]}],"complexes":["trans-Golgi network tethering apparatus"],"partners":["RAB9A","RAB6A","ARL1","ARL4A","AP-1","CLASP1","CLASP2","HIV-1 NEF"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"Q8IWJ2","full_name":"GRIP and coiled-coil domain-containing protein 2","aliases":["185 kDa Golgi coiled-coil protein","GCC185","CLL-associated antigen KW-11","CTCL tumor antigen se1-1","Ran-binding protein 2-like 4","RanBP2L4","Renal carcinoma antigen NY-REN-53"],"length_aa":1684,"mass_kda":195.9,"function":"Golgin which probably tethers transport vesicles to the trans-Golgi network (TGN) and regulates vesicular transport between the endosomes and the Golgi. As a RAB9A effector it is involved in recycling of the mannose 6-phosphate receptor from the late endosomes to the TGN. May also play a role in transport between the recycling endosomes and the Golgi. Required for maintenance of the Golgi structure, it is involved in the biogenesis of noncentrosomal, Golgi-associated microtubules through recruitment of CLASP1 and CLASP2","subcellular_location":"Cytoplasm; Golgi apparatus, trans-Golgi network membrane","url":"https://www.uniprot.org/uniprotkb/Q8IWJ2/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/GCC2","classification":"Not Classified","n_dependent_lines":0,"n_total_lines":1208,"dependency_fraction":0.0},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[{"gene":"CLASP2","stoichiometry":10.0},{"gene":"CLASP1","stoichiometry":4.0},{"gene":"PSMB1","stoichiometry":0.2},{"gene":"PSMD13","stoichiometry":0.2},{"gene":"PSMD2","stoichiometry":0.2},{"gene":"TUBA1B","stoichiometry":0.2},{"gene":"TUBB4B","stoichiometry":0.2}],"url":"https://opencell.sf.czbiohub.org/search/GCC2","total_profiled":1310},"omim":[{"mim_id":"614048","title":"ENDOSOME-LYSOSOME-ASSOCIATED APOPTOSIS AND AUTOPHAGY REGULATOR 2; ELAPOR2","url":"https://www.omim.org/entry/614048"},{"mim_id":"612711","title":"GRIP AND COILED-COIL DOMAIN-CONTAINING PROTEIN 2; GCC2","url":"https://www.omim.org/entry/612711"},{"mim_id":"612710","title":"RANBP2-LIKE AND GRIP DOMAIN-CONTAINING PROTEIN 7; RGPD7","url":"https://www.omim.org/entry/612710"},{"mim_id":"612709","title":"RANBP2-LIKE AND GRIP DOMAIN-CONTAINING PROTEIN 6; RGPD6","url":"https://www.omim.org/entry/612709"},{"mim_id":"612708","title":"RANBP2-LIKE AND GRIP DOMAIN-CONTAINING PROTEIN 5; RGPD5","url":"https://www.omim.org/entry/612708"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Enhanced","locations":[{"location":"Golgi apparatus","reliability":"Enhanced"},{"location":"Nucleoplasm","reliability":"Additional"}],"tissue_specificity":"Low tissue specificity","tissue_distribution":"Detected in all","driving_tissues":[],"url":"https://www.proteinatlas.org/search/GCC2"},"hgnc":{"alias_symbol":["GCC185","KIAA0336"],"prev_symbol":[]},"alphafold":{"accession":"Q8IWJ2","domains":[{"cath_id":"1.20.5","chopping":"29-58","consensus_level":"medium","plddt":74.2347,"start":29,"end":58}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q8IWJ2","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q8IWJ2-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q8IWJ2-F1-predicted_aligned_error_v6.png","plddt_mean":71.69},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=GCC2","jax_strain_url":"https://www.jax.org/strain/search?query=GCC2"},"sequence":{"accession":"Q8IWJ2","fasta_url":"https://rest.uniprot.org/uniprotkb/Q8IWJ2.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q8IWJ2/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q8IWJ2"}},"corpus_meta":[{"pmid":"18243103","id":"PMC_18243103","title":"Rab and Arl GTPase family members cooperate in the localization of the golgin GCC185.","date":"2008","source":"Cell","url":"https://pubmed.ncbi.nlm.nih.gov/18243103","citation_count":140,"is_preprint":false},{"pmid":"17488291","id":"PMC_17488291","title":"The trans-Golgi network golgin, GCC185, is required for endosome-to-Golgi transport and maintenance of Golgi structure.","date":"2007","source":"Traffic (Copenhagen, Denmark)","url":"https://pubmed.ncbi.nlm.nih.gov/17488291","citation_count":121,"is_preprint":false},{"pmid":"12446665","id":"PMC_12446665","title":"GRIP domain-mediated targeting of two new coiled-coil proteins, GCC88 and GCC185, to subcompartments of the trans-Golgi network.","date":"2002","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/12446665","citation_count":110,"is_preprint":false},{"pmid":"16885419","id":"PMC_16885419","title":"A functional role for the GCC185 golgin in mannose 6-phosphate receptor recycling.","date":"2006","source":"Molecular biology of the cell","url":"https://pubmed.ncbi.nlm.nih.gov/16885419","citation_count":103,"is_preprint":false},{"pmid":"18946081","id":"PMC_18946081","title":"Multiple Rab GTPase binding sites in GCC185 suggest a model for vesicle tethering at the trans-Golgi.","date":"2008","source":"Molecular biology of the cell","url":"https://pubmed.ncbi.nlm.nih.gov/18946081","citation_count":84,"is_preprint":false},{"pmid":"19703403","id":"PMC_19703403","title":"The localization of the Golgin GCC185 is independent of Rab6A/A' and Arl1.","date":"2009","source":"Cell","url":"https://pubmed.ncbi.nlm.nih.gov/19703403","citation_count":38,"is_preprint":false},{"pmid":"21875948","id":"PMC_21875948","title":"GCC185 plays independent roles in Golgi structure maintenance and AP-1-mediated vesicle tethering.","date":"2011","source":"The Journal of cell biology","url":"https://pubmed.ncbi.nlm.nih.gov/21875948","citation_count":35,"is_preprint":false},{"pmid":"22159419","id":"PMC_22159419","title":"ARL4A acts with GCC185 to modulate Golgi complex organization.","date":"2011","source":"Journal of cell science","url":"https://pubmed.ncbi.nlm.nih.gov/22159419","citation_count":32,"is_preprint":false},{"pmid":"29290262","id":"PMC_29290262","title":"GCC2-ALK as a targetable fusion in lung adenocarcinoma and its enduring clinical responses to ALK inhibitors.","date":"2017","source":"Lung cancer (Amsterdam, Netherlands)","url":"https://pubmed.ncbi.nlm.nih.gov/29290262","citation_count":25,"is_preprint":false},{"pmid":"34771645","id":"PMC_34771645","title":"GCC2 as a New Early Diagnostic Biomarker for Non-Small Cell Lung Cancer.","date":"2021","source":"Cancers","url":"https://pubmed.ncbi.nlm.nih.gov/34771645","citation_count":24,"is_preprint":false},{"pmid":"36003768","id":"PMC_36003768","title":"Case Report: Efficacy of ensartinib treatment in pulmonary inflammatory myofibroblastic tumor with a rare GCC2-ALK fusion.","date":"2022","source":"Frontiers in oncology","url":"https://pubmed.ncbi.nlm.nih.gov/36003768","citation_count":8,"is_preprint":false},{"pmid":"27105913","id":"PMC_27105913","title":"HIV-1 Nef binds with human GCC185 protein and regulates mannose 6 phosphate receptor recycling.","date":"2016","source":"Biochemical and biophysical research communications","url":"https://pubmed.ncbi.nlm.nih.gov/27105913","citation_count":7,"is_preprint":false},{"pmid":"39572606","id":"PMC_39572606","title":"GCC2 promotes non-small cell lung cancer progression by maintaining Golgi apparatus integrity and stimulating EGFR signaling pathways.","date":"2024","source":"Scientific reports","url":"https://pubmed.ncbi.nlm.nih.gov/39572606","citation_count":5,"is_preprint":false},{"pmid":"30697976","id":"PMC_30697976","title":"A novel fusion gene involving PDGFRB and GCC2 in a chronic eosinophilic leukemia patient harboring t(2;5)(q37;q31).","date":"2019","source":"Molecular genetics & genomic medicine","url":"https://pubmed.ncbi.nlm.nih.gov/30697976","citation_count":5,"is_preprint":false},{"pmid":"35116968","id":"PMC_35116968","title":"Rare GCC2-ALK fusion G13:A20 detected by next generation sequencing in non-small cell lung cancer patients and treatment response.","date":"2019","source":"Translational cancer research","url":"https://pubmed.ncbi.nlm.nih.gov/35116968","citation_count":4,"is_preprint":false},{"pmid":"30953643","id":"PMC_30953643","title":"HIV-1 Nef-GCC185 interaction regulates assembly of cellular protein complexes at TGN targeting MHC-I downregulation.","date":"2019","source":"Life sciences","url":"https://pubmed.ncbi.nlm.nih.gov/30953643","citation_count":2,"is_preprint":false},{"pmid":"25702118","id":"PMC_25702118","title":"Molecular and cellular characterization of GCC185: a tethering protein of the trans-Golgi network.","date":"2015","source":"Methods in molecular biology (Clifton, N.J.)","url":"https://pubmed.ncbi.nlm.nih.gov/25702118","citation_count":2,"is_preprint":false},{"pmid":"36650585","id":"PMC_36650585","title":"Differential paired stage-specific expression of Babesia bovis cysteine-rich GCC2/GCC3 domain family proteins (BboGDP) during development within Rhipicephalus microplus.","date":"2023","source":"Parasites & vectors","url":"https://pubmed.ncbi.nlm.nih.gov/36650585","citation_count":2,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":10116,"output_tokens":3305,"usd":0.039961,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":10758,"output_tokens":3220,"usd":0.067145,"stage2_stop_reason":"end_turn"},"total_usd":0.107106,"stage1_batch_id":"msgbatch_01DUPACZi7AAWwuZiUjseQF4","stage2_batch_id":"msgbatch_018yt7chE3f48PEFtDwtj6AE","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2002,\n      \"finding\": \"GCC185 (GCC2) is a peripheral membrane protein with a C-terminal GRIP domain that targets it to the trans-Golgi network (TGN); the GRIP domain is necessary and sufficient for TGN targeting, and GCC185 localizes to a TGN subcompartment distinct from alpha2,6-sialyltransferase and cis-Golgi markers.\",\n      \"method\": \"Immunofluorescence, immunoelectron microscopy, overexpression of full-length and truncated constructs in HeLa cells\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — direct localization experiment with domain mapping, replicated across multiple constructs and imaging modalities, foundational characterization paper\",\n      \"pmids\": [\"12446665\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2006,\n      \"finding\": \"GCC185 (GCC2) is a Rab9 effector required for mannose 6-phosphate receptor (MPR) recycling from late endosomes to the TGN; depletion of GCC185 triggers enhanced MPR degradation and elevated secretion of hexosaminidase, and GCC185 functions in MPR recycling both in living cells and in vitro.\",\n      \"method\": \"siRNA depletion, in vitro transport assay, functional rescue, hexosaminidase secretion assay\",\n      \"journal\": \"Molecular biology of the cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — multiple orthogonal functional assays (in vitro and in vivo), siRNA depletion with specific phenotypic readouts, replicated in subsequent studies\",\n      \"pmids\": [\"16885419\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"GCC185 (GCC2) is essential for endosome-to-TGN transport of shiga toxin (which accumulates in Rab11-positive recycling endosomes upon GCC185 depletion) and for maintaining Golgi ribbon organization; depletion causes Golgi fragmentation with dispersal of both cis and trans markers, while TGN38 recycling and anterograde E-cadherin transport are initially unaffected.\",\n      \"method\": \"siRNA and miRNA depletion in HeLa cells, shiga toxin trafficking assay, mannose-6-phosphate receptor distribution, immunofluorescence\",\n      \"journal\": \"Traffic (Copenhagen, Denmark)\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — two independent knockdown methods (siRNA and miRNA), multiple cargo readouts, replicated findings consistent with prior work\",\n      \"pmids\": [\"17488291\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"GCC185 (GCC2) is recruited to the Golgi by cooperative interaction with two small GTPases: Rab6 binds a coiled-coil domain immediately adjacent to the C-terminal GRIP domain, and Rab6 binding promotes association of Arl1 with the GRIP domain; crystal structure of Rab6 bound to the GCC185 Rab-binding domain reveals Rab6 recognizes a two-fold symmetric surface on the coiled coil.\",\n      \"method\": \"Crystal structure determination, mutagenesis of Rab-binding residues, Golgi localization assay, in vitro binding assays\",\n      \"journal\": \"Cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — crystal structure plus mutagenesis plus localization assay in a single study; however, contradicted by a subsequent study (PMID:19703403)\",\n      \"pmids\": [\"18243103\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"GCC185 (GCC2) contains at least four additional Rab GTPase binding sites distributed across its length that can bind up to 14 different Rab GTPases; a central coiled-coil domain contains a specific Rab9 binding site that is functionally important for MPR recycling to the Golgi.\",\n      \"method\": \"Yeast two-hybrid, direct biochemical binding assays, siRNA depletion with plasmid rescue, functional MPR recycling assay\",\n      \"journal\": \"Molecular biology of the cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — yeast two-hybrid combined with direct biochemical tests and functional rescue assays, multiple Rab binding sites mapped across the protein\",\n      \"pmids\": [\"18946081\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2009,\n      \"finding\": \"Endogenous GCC185 (GCC2) Golgi localization does not require Rab6A/A' or Arl1; depletion of both Rab6A/A' and Arl1 had no effect on localization of endogenous GCC185 or its isolated GRIP domain, and minimal colocalization between Rab6A/A' and endogenous GCC185 was detected on Golgi membranes.\",\n      \"method\": \"Rab6A/A' and Arl1 depletion (siRNA), yeast two-hybrid (negative result for Rab6A/A' interaction with GCC185 C-terminal domain), immunofluorescence colocalization\",\n      \"journal\": \"Cell\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — negative result contradicting PMID:18243103, using endogenous protein and two orthogonal methods; single lab, contradicts prior crystal structure-based model\",\n      \"pmids\": [\"19703403\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"GCC185 (GCC2) contains two functionally distinct domains: one required for Golgi structure maintenance and a separate domain required for vesicle tethering that directly binds the clathrin adaptor AP-1; cells depleted of GCC185 accumulate MPRs in AP-1-decorated transport vesicles, indicating GCC185 tethers AP-1-coated vesicles carrying MPRs from late endosomes to the TGN.\",\n      \"method\": \"Domain deletion/rescue experiments, co-immunoprecipitation of AP-1, siRNA depletion with vesicle accumulation assay, immunofluorescence\",\n      \"journal\": \"The Journal of cell biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — domain dissection with functional rescue, AP-1 interaction identified by co-IP, vesicle accumulation phenotype providing mechanistic insight into two independent functions\",\n      \"pmids\": [\"21875948\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"ARL4A directly interacts with GCC185 (GCC2) in a GTP-dependent manner via the CC2 coiled-coil sub-domain of GCC185; this interaction is required for GCC185 to recruit CLASP1 and CLASP2 to the Golgi, which is necessary for Golgi structure maintenance. Depletion of ARL4A impairs GCC185–CLASP interaction and phenocopies GCC185 depletion (Golgi fragmentation, endosome-to-Golgi transport defects).\",\n      \"method\": \"Co-immunoprecipitation, GST pulldown, siRNA depletion of ARL4A, domain deletion mapping, CLASP recruitment assay\",\n      \"journal\": \"Journal of cell science\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — reciprocal co-IP, domain mapping, functional phenocopy by ARL4A depletion, CLASP recruitment assay provide multiple orthogonal lines of evidence\",\n      \"pmids\": [\"22159419\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"HIV-1 Nef binds to GCC185 (GCC2) via the N-terminal EEEE65 acidic domain of Nef; this interaction disrupts GCC185–Rab9 interaction, causing delocalization of CI-MPR and elevated hexosaminidase secretion, thereby disrupting retrograde vesicular transport from late endosomes to the TGN.\",\n      \"method\": \"Co-immunoprecipitation, C. elegans screen followed by biochemical characterization, hexosaminidase secretion assay, CI-MPR localization assay\",\n      \"journal\": \"Biochemical and biophysical research communications\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Weak — single lab, co-IP-based interaction mapping with functional readout, but limited orthogonal validation\",\n      \"pmids\": [\"27105913\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"The GCC2-ALK fusion protein acts as a constitutively activated oncogenic kinase: it promotes IL-3-independent growth of Ba/F3 cells and leads to hyper-activation of ALK downstream signaling (MAPK, PI3K, STAT3 pathways) in HEK-293 and 293T cells; this activation is inhibited by crizotinib.\",\n      \"method\": \"Ba/F3 cell proliferation assay (IL-3 independence), ectopic expression in HEK-293/293T cells, western blot for downstream signaling, crizotinib inhibition assay\",\n      \"journal\": \"Lung cancer (Amsterdam, Netherlands)\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — cell-based functional assays with signaling pathway readouts in two cell systems, single lab\",\n      \"pmids\": [\"29290262\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"HIV-1 Nef assembles a multi-protein complex at the TGN through GCC185 (GCC2) as a focal scaffold; GCC185-dependent complex includes MHC-I and SFK, while Nef-dependent components include AP-1 and PI3K; siRNA knockdown of GCC185 in Jurkat T cells causes MHC-I accumulation at GCC185, linking GCC185 to Nef-mediated MHC-I downregulation.\",\n      \"method\": \"Co-immunoprecipitation in Jurkat T and THP-1 cells, siRNA knockdown of GCC185, confocal microscopy, flow cytometry for MHC-I surface levels\",\n      \"journal\": \"Life sciences\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — multiple co-IPs with different antibodies and cell types, siRNA knockdown phenotype, but single lab and relatively limited mechanistic dissection\",\n      \"pmids\": [\"30953643\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"GCC2 knockdown in NSCLC cells decreases EGFR expression and suppresses downstream growth/proliferation signaling, while also compromising Golgi structural integrity and reducing exosome secretion; these results indicate GCC2 regulates EGFR signaling and intracellular trafficking in cancer cells.\",\n      \"method\": \"shRNA-mediated GCC2 knockdown, western blot for EGFR and downstream signaling, cell proliferation/migration/EMT assays, Golgi morphology imaging, exosome secretion assay, in vivo xenograft\",\n      \"journal\": \"Scientific reports\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — shRNA knockdown with multiple phenotypic readouts and in vivo validation, but mechanistic link between GCC2 and EGFR regulation is not molecularly dissected\",\n      \"pmids\": [\"39572606\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"GCC2 (GCC185) is a large coiled-coil tethering protein of the trans-Golgi network that is recruited to the Golgi via its C-terminal GRIP domain and interactions with small GTPases (including ARL4A), where it performs at least two independent functions: (1) tethering of AP-1-decorated, Rab9-bearing transport vesicles carrying mannose 6-phosphate receptors from late endosomes to the TGN, and (2) maintaining Golgi ribbon integrity by recruiting CLASP1/2 microtubule-associated proteins through an ARL4A-dependent mechanism; additionally, GCC2 can be co-opted by HIV-1 Nef as a scaffold for multi-protein complex assembly that mediates MHC-I downregulation, and GCC2 chromosomal rearrangements create constitutively active GCC2-ALK and GCC2-PDGFRB oncogenic fusion kinases.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"GCC2 (GCC185) is a peripheral membrane coiled-coil tethering protein of the trans-Golgi network (TGN) that coordinates retrograde vesicle capture and Golgi ribbon architecture [#0, #6]. Its C-terminal GRIP domain is necessary and sufficient for targeting to a distinct TGN subcompartment [#0], and the protein is recruited and oriented through interactions with small GTPases, binding up to 14 Rab GTPases across multiple sites along its length, including a functionally critical central Rab9-binding site [#4]. Through this Rab9-effector activity GCC2 mediates recycling of mannose 6-phosphate receptors (MPRs) from late endosomes to the TGN, such that its depletion drives MPR mis-sorting, enhanced MPR degradation, and elevated lysosomal hydrolase secretion [#1]; the same retrograde route delivers shiga toxin to the Golgi [#2]. GCC2 separates these activities into discrete domains: a vesicle-tethering domain that directly binds the clathrin adaptor AP-1 to capture MPR-laden, AP-1-decorated transport vesicles, and a separate domain dedicated to maintaining Golgi structure [#6]. Golgi ribbon integrity is sustained through a GTP-dependent interaction with ARL4A via the CC2 coiled-coil sub-domain, which licenses GCC2 to recruit the microtubule-associated proteins CLASP1 and CLASP2 to the Golgi [#7]. GCC2 is co-opted in disease contexts: HIV-1 Nef binds GCC2 to disrupt the GCC2–Rab9 interaction and impair retrograde transport [#8], and uses GCC2 as a focal scaffold to assemble a multi-protein complex driving MHC-I downregulation [#10]; chromosomal rearrangement generates a constitutively active GCC2-ALK oncogenic fusion kinase that hyperactivates MAPK, PI3K, and STAT3 signaling and is sensitive to crizotinib [#9].\",\n  \"teleology\": [\n    {\n      \"year\": 2002,\n      \"claim\": \"Established where GCC2 acts in the cell and how it is targeted there, defining it as a GRIP-domain TGN protein occupying a distinct subcompartment.\",\n      \"evidence\": \"Immunofluorescence, immunoelectron microscopy, and truncation constructs in HeLa cells\",\n      \"pmids\": [\"12446665\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Did not identify the GTPase or lipid partners mediating GRIP-domain recruitment\", \"No functional role assigned\"]\n    },\n    {\n      \"year\": 2006,\n      \"claim\": \"Assigned GCC2 a concrete transport function by showing it is a Rab9 effector required for MPR recycling from late endosomes to the TGN.\",\n      \"evidence\": \"siRNA depletion, in vitro transport assay, functional rescue, hexosaminidase secretion assay\",\n      \"pmids\": [\"16885419\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Molecular mechanism of vesicle capture not resolved\", \"Did not distinguish tethering from sorting roles\"]\n    },\n    {\n      \"year\": 2007,\n      \"claim\": \"Broadened GCC2 function to general retrograde endosome-to-TGN transport and revealed a second, separable role in Golgi ribbon organization.\",\n      \"evidence\": \"siRNA and miRNA depletion in HeLa cells, shiga toxin trafficking and MPR distribution assays\",\n      \"pmids\": [\"17488291\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Did not determine whether transport and structural defects share a mechanism\", \"Cargo selectivity of the retrograde pathway unexplained\"]\n    },\n    {\n      \"year\": 2008,\n      \"claim\": \"Mapped the GTPase code recruiting and orienting GCC2, identifying Rab6/Arl1 cooperative recruitment at the C-terminus and a dispersed set of Rab-binding sites including a functional Rab9 site.\",\n      \"evidence\": \"Crystal structure of Rab6–GCC2 RBD, mutagenesis, yeast two-hybrid, biochemical binding, and functional rescue assays\",\n      \"pmids\": [\"18243103\", \"18946081\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"The Rab6/Arl1 recruitment model was contradicted for endogenous protein\", \"Functional significance of most of the 14 Rab interactions undefined\"]\n    },\n    {\n      \"year\": 2009,\n      \"claim\": \"Challenged the Rab6/Arl1 recruitment model by showing endogenous GCC2 Golgi localization is independent of Rab6A/A' and Arl1.\",\n      \"evidence\": \"Rab6A/A' and Arl1 siRNA depletion, yeast two-hybrid, and colocalization on endogenous protein\",\n      \"pmids\": [\"19703403\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Negative result from a single lab contradicting prior crystal structure work\", \"Did not identify the alternative endogenous recruitment determinant\"]\n    },\n    {\n      \"year\": 2011,\n      \"claim\": \"Resolved GCC2 into two molecularly distinct activities and identified the direct tethering partner, showing one domain binds AP-1 to capture MPR-laden vesicles while a separate domain maintains Golgi structure.\",\n      \"evidence\": \"Domain deletion/rescue, AP-1 co-IP, siRNA with vesicle accumulation assay; and ARL4A GTP-dependent co-IP/GST pulldown with CLASP recruitment assay\",\n      \"pmids\": [\"21875948\", \"22159419\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"How CLASP recruitment maintains ribbon integrity mechanistically unresolved\", \"Coupling between AP-1 tethering and Rab9/MPR sorting not detailed\"]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Showed GCC2 is exploited as a viral scaffold, with HIV-1 Nef binding GCC2 to disrupt Rab9 association and assemble a TGN complex driving MHC-I downregulation.\",\n      \"evidence\": \"Co-IP in Jurkat T and THP-1 cells, siRNA knockdown, confocal microscopy, hexosaminidase and MHC-I flow cytometry\",\n      \"pmids\": [\"27105913\", \"30953643\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Single-lab interaction mapping with limited orthogonal validation\", \"Stoichiometry and architecture of the Nef-GCC2 complex undefined\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Linked GCC2 to cancer cell biology, both as a constitutively active fusion kinase (GCC2-ALK) and as a regulator of EGFR signaling and trafficking when its levels are altered.\",\n      \"evidence\": \"Ba/F3 IL-3 independence and crizotinib assays for GCC2-ALK; shRNA knockdown with EGFR/signaling readouts, Golgi imaging, exosome and xenograft assays for NSCLC\",\n      \"pmids\": [\"29290262\", \"39572606\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Molecular link between GCC2 and EGFR regulation not dissected\", \"Whether EGFR effects are secondary to Golgi/trafficking disruption unclear\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"The endogenous determinant of GCC2 Golgi recruitment and the mechanism coupling its tethering, GTPase-binding, and structural roles remain unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Reconciliation of the Rab6/Arl1 crystal model with the negative endogenous-depletion result is unsettled\", \"No unified mechanism connecting CLASP-dependent ribbon maintenance to vesicle tethering\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0060090\", \"supporting_discovery_ids\": [6]},\n      {\"term_id\": \"GO:0008092\", \"supporting_discovery_ids\": [7]},\n      {\"term_id\": \"GO:0098772\", \"supporting_discovery_ids\": [3, 4]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005794\", \"supporting_discovery_ids\": [0, 2]},\n      {\"term_id\": \"GO:0005802\", \"supporting_discovery_ids\": [0]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-5653656\", \"supporting_discovery_ids\": [1, 2, 6]},\n      {\"term_id\": \"R-HSA-9609507\", \"supporting_discovery_ids\": [1, 6]},\n      {\"term_id\": \"R-HSA-1852241\", \"supporting_discovery_ids\": [2, 7]}\n    ],\n    \"complexes\": [\"trans-Golgi network tethering apparatus\"],\n    \"partners\": [\"RAB9A\", \"RAB6A\", \"ARL1\", \"ARL4A\", \"AP-1\", \"CLASP1\", \"CLASP2\", \"HIV-1 Nef\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":6,"faith_total":6,"faith_pct":100.0}}