| 2000 |
GGA2 (Vear) is a Golgi-localized protein with an N-terminal VHS domain and a C-terminal gamma-adaptin 'ear' domain. Full-length GGA2 and truncated forms lacking the VHS domain cause compaction of the Golgi complex upon overexpression; the ear domain alone associates with the Golgi without compaction; the VHS domain alone shows diffuse membrane/vesicle distribution. GGA2 partitions with the post-nuclear membrane fraction on cell fractionation. |
Immunofluorescence microscopy, cell fractionation, brefeldin A treatment, transfection of truncation constructs |
The Journal of biological chemistry |
Medium |
10702286
|
| 2001 |
The VHS domain of GGA2 binds to the acidic cluster-dileucine motif in the cytoplasmic tail of the cation-independent mannose 6-phosphate receptor (CI-MPR). This interaction is required for lysosomal enzyme sorting: receptors with mutations in this motif are defective in sorting. The hinge domain of GGA2 binds clathrin, suggesting GGA2 links cargo to clathrin-coated vesicle assembly. |
Binding assays (VHS domain with CI-MPR cytoplasmic tail peptides), mutagenesis of the acidic cluster-dileucine motif, clathrin-binding assay with GGA2 hinge domain |
Science (New York, N.Y.) |
High |
11387476
|
| 2001 |
The VHS domain of GGA2 binds the cytoplasmic tail of sortilin via YXX and dileucine sorting motifs, and sortilin chimeric receptors containing the sortilin tail efficiently transport lysosomal enzymes (beta-hexosaminidase, beta-glucuronidase) to lysosomes in MPR-knockout cells, identifying sortilin as the first mammalian receptor targeted by the GGA family. |
Chimeric receptor expression in MPR-knockout cells, lysosomal enzyme transport assay, VHS domain binding to sortilin cytoplasmic tail |
The EMBO journal |
High |
11331584
|
| 2002 |
The VHS domains of GGA1 and GGA2 bind the cytosolic domain of memapsin 2 (beta-secretase/BACE1). Mutagenesis identified Asp496, Leu499, and Leu500 as essential residues in memapsin 2 for this interaction, matching the spacing found in CI-MPR, sortilin, and LRP3 cytoplasmic tails. Gel-immobilized VHS domains of GGA2 pull down full-length memapsin 2 from mammalian cell lysates. |
Pulldown assay with immobilized VHS domains, mammalian cell lysate pulldown, site-directed mutagenesis of memapsin 2 cytoplasmic domain |
FEBS letters |
Medium |
12135764
|
| 2007 |
Specific RNAi-mediated depletion of GGA2 (to ~5% of control levels) in HeLa cells increases secretion of the lysosomal enzyme cathepsin D without altering the distribution of GGA1, GGA3, or MPRs, establishing a non-redundant role for GGA2 in lysosomal enzyme sorting at the TGN. The dominant-negative VHS-GAT domain of GGA2 is recruited to the TGN independently of GGA1 and GGA3. |
Stable RNAi knockdown cell lines, cathepsin D secretion assay, immunofluorescence for TGN markers, dominant-negative domain expression |
Archives of histology and cytology |
Medium |
18431031
|
| 2009 |
In yeast, Gga2 is required for TGN-to-vacuole sorting of the iron transporter Arn1p. Ubiquitin binding by Gga2 is NOT required for the initial TGN-to-endosome step but IS required for subsequent multivesicular body sorting of Arn1p: a ubiquitin-binding mutant of Gga2 causes accumulation of ubiquitinated Arn1p on the vacuolar membrane. Yeast epsins Ent3p and Ent4p also participate. N-terminal sequences of Arn1p (THN and YGL motifs, ubiquitinatable lysines) are required for vacuolar sorting. |
Yeast genetics, ubiquitin-binding mutant analysis, fluorescence microscopy of GFP-tagged Arn1p, mutagenesis of Arn1p sorting motifs |
The Journal of biological chemistry |
High |
19574226
|
| 2012 |
GGA2 knockout mice (using the Tigm gene-trap allele) show neonatal lethality, whereas GGA1 or GGA3 single knockouts are well tolerated. This establishes a non-redundant, essential in vivo function for GGA2 that cannot be compensated by GGA1 or GGA3. |
Insertional mutagenesis, mouse knockout analysis, neonatal viability phenotyping |
PloS one |
High |
22291915
|
| 2014 |
The Byg Gga2 gene-trap allele is hypomorphic (residual GGA2 expression), while the Tigm allele is a true null; neonatal lethality of Tigm Gga2−/− mice is influenced by genetic background (C57BL/6 vs. mixed C57BL6/Ola129Sv). Surviving Gga2−/− mice show reduced birth weight maintained through adulthood. |
Gene-trap allele characterization, Western blotting, cross-breeding to different genetic backgrounds, growth curve analysis |
G3 (Bethesda, Md.) |
Medium |
24637350
|
| 2016 |
GGA2 (and GGA1) are required for cell-surface transport of α2B-adrenergic receptor (α2B-AR). Knockdown of GGA2 arrests newly synthesized α2B-AR in the perinuclear region and reduces dendritic receptor expression in cortical neurons. The third intracellular loop of α2B-AR directly interacts with both GGA1 and GGA2; the GAE (gamma-adaptin ear) domain of GGA2 (and the hinge of GGA1) binds multiple subdomains of this loop. Full-length α2B-AR co-immunoprecipitates with GGA2 but not GGA1. |
shRNA/siRNA knockdown, co-immunoprecipitation, domain-mapping pulldown assays, primary cortical neuron imaging, ERK1/2 and cAMP signaling assays |
Scientific reports |
Medium |
27901063
|
| 2018 |
GGA2 interacts with the cytoplasmic juxtamembrane region (jxt) of EGFR via its VHS-GAT domains in a manner dependent on Asn108 in the VHS domain. GGA2 depletion greatly reduces steady-state EGFR expression by enhancing lysosomal degradation; this effect is reversed by additional depletion of GGA1 or GGA3, indicating GGA1/GGA3 promote EGFR degradation while GGA2 counteracts this. GGA2 depletion reduces EGF signaling and cell proliferation in vitro and in xenograft models. |
RNAi knockdown, pulldown assays with VHS-GAT domain constructs, proximity ligation assay, mutagenesis (N108), rescue by double knockdown, xenograft tumor model |
Scientific reports |
High |
29358589
|
| 2018 |
GGA2 interacts with EGFR (co-immunoprecipitation), increases EGFR protein levels, and modifies EGFR degradation after ligand stimulation. GGA2 overexpression enhances EGFR-mediated cellular transformation; GGA2 knockdown reduces colony and tumor formation of EGFR-mutant lung adenocarcinoma cells. |
Co-immunoprecipitation, Western blot, RNAi knockdown, gene overexpression, colony formation assay, in vivo tumor models |
Journal of thoracic oncology |
Medium |
30578931
|
| 2019 |
GGA2 associates with active (but not inactive) β1-integrin and is required for recycling of active β1-integrin receptors to the plasma membrane. GGA2 silencing reduces active β1-integrin in focal adhesions and decreases cancer cell migration and invasion. BioID proximity labeling identified RAB13 and RAB10 as GGA2 interactors; RAB13 silencing phenocopies GGA2 depletion (intracellular accumulation of active β1-integrin, reduced focal adhesion levels, reduced migration), placing GGA2 and RAB13 in the same active integrin recycling pathway. |
RNAi screen, co-immunoprecipitation, BioID proximity labeling, integrin activity assay (active-conformation antibody), focal adhesion imaging, migration/invasion assays |
Journal of cell science |
High |
31076515
|
| 2020 |
In yeast, Gga2 is required for maximal vacuolar delivery of amino acid permeases (Mup1, Can1, and others) during acute glucose starvation. Endocytosed Can1 transits through the TGN under both starved and glucose-replete conditions, and TGN-localized clathrin adaptors (including Gga2) are required for vacuolar sorting in both states. Forced de-ubiquitination at the TGN causes recycling of Tat1 permease in starved cells, showing active sorting to the vacuole. AP-1 plays only a minor role. |
Fluorescence microscopy of GFP-tagged permeases, genetic deletion of clathrin adaptors, ectopic de-ubiquitination at TGN |
Biology of the cell |
Medium |
32761633
|
| 2021 |
GGA2 and AP-1 both support EGFR recycling from Rab11-positive recycling endosomes to the plasma membrane (rather than acting solely at the TGN). Depletion of AP-1 or GGA2 suppresses EGFR recycling and reduces cell-surface levels of EGFR, MET, and ErbB4, reducing cancer cell growth. Triple immunofluorescence and proximity ligation assays showed EGFR interaction with GGA2 or AP-1 more frequently at Rab11-positive endosomes than Rab5-positive early endosomes. |
Biochemical recycling assay, triple immunofluorescence microscopy, proximity ligation assay, RNAi depletion, xenograft model |
Oncogenesis |
High |
34799560
|
| 2025 |
GGA2 is rapidly depleted in pancreatic beta cells by Coxsackievirus B5 protease 2A (due to its short half-life). GGA2 depletion impairs insulin secretory granule biogenesis at the TGN, disrupts sorting of vacuolar ATPase and cathepsins, causes TGN acidification, and leads to premature lysosomal hydrolase activation. These changes alter the HLA-I immunopeptidome, shifting it towards HLA-B–presented, low-pI peptides generated by cathepsin-mediated processing of in-transit secretory proteins. |
CVB5 infection of beta cells, GGA2 depletion (siRNA/viral), immunostaining of pancreas sections from T1D donors, mass spectrometry of immunopeptidome, TGN pH measurement |
bioRxivpreprint |
Medium |
bio_10.1101_2025.03.28.645506
|