GOLGA1

Golgin-97 (GOLGA1) is a trans-Golgi network (TGN) coiled-coil tethering protein that captures endosome- and recycling-endosome-derived transport carriers and promotes selective export of basolateral cargoes from the TGN (PMID:28122620, PMID:16262725). It is recruited to the TGN through a C-terminal ~50-residue GRIP domain that is necessary and sufficient for Golgi targeting (PMID:10209120, PMID:10209123, PMID:10209125); targeting requires a three-tier hierarchy in which the GRIP domain first self-dimerizes, then bivalently engages the activated GTPase Arl1, and finally contacts membrane lipids directly through basic and hydrophobic residues flanking the domain (PMID:16899086, PMID:15654769). Arl1 itself depends on the upstream regulator ARFRP1 for its own Golgi localization, placing golgin-97 at the bottom of an ARFRP1→Arl1→golgin-97 recruitment cascade that governs both anterograde and retrograde TGN transport (PMID:16129887); Arl1 stability is required continuously, as its oxidative degradation strips golgin-97 from the membrane (PMID:32583744). At its exposed N-terminus, a short capture motif shared with golgin-245 docks incoming vesicles via the bridging adaptor TBC1D23, whose rhodanese-TBC platform binds the golgin tip while its C-terminal domain engages the WASH complex on endosomal vesicles and recognizes an acidic TLY cargo motif, thereby conferring endosome-to-Golgi specificity (PMID:28122620, PMID:29084197, PMID:38552021, PMID:32453802). Golgin-97 selectively mediates TGN export of E-cadherin and the potassium channel Kir2.1, the latter through direct GRIP-domain binding, and its E-cadherin/VSVG export function is gated by PARP12-mediated mono-ADP-ribosylation of an acidic cluster in its coiled-coil, downstream of PKD activation (PMID:16262725, PMID:30123141, PMID:34969853). Independently of its Golgi role, golgin-97 suppresses NF-κB activity by maintaining IκBα levels, a function exhibited by both membrane-bound and cytosolic pools (PMID:29703230).

1. 1999 High

   Establishing how golgin-97 reaches the Golgi, the C-terminal GRIP domain was defined as a transferable, self-contained Golgi-targeting determinant and the conserved aromatic/tyrosine residues required for it were mapped.

   Evidence GFP-GRIP fusion targeting, site-directed mutagenesis, and competitive displacement in mammalian cells

   PMID:10209120 PMID:10209123 PMID:10209125

   Open questions at the time

   • Did not identify the membrane determinant the GRIP domain recognizes
   • Rab6 binding on blots was later superseded by Arl1 as the primary targeting GTPase
2. 2003 Medium

   Dominant-negative GRIP-domain overexpression showed golgin-97 is functionally required for TGN-to-plasma-membrane transport and TGN organization, moving it from a localization marker to a trafficking effector.

   Evidence Isolated GRIP-domain overexpression with EM, transport and furin-cleavage assays, and a tyrosine mutant control

   PMID:13130094

   Open questions at the time

   • Overexpression of an isolated fragment may act non-physiologically
   • No direct cargo or vesicle partner identified
3. 2005 Medium

   The targeting GTPase and the upstream cascade were resolved: Arl1-GTP recruits golgin-97 via the GRIP domain, and ARFRP1 is required upstream to position Arl1, distinguishing golgin-97 from Arl1-independent GRIP golgins.

   Evidence Co-IP, in vivo GRIP overexpression and colocalization, plus siRNA of ARFRP1 with VSV-G and Shiga toxin transport assays

   PMID:15522892 PMID:16129887

   Open questions at the time

   • Quantitative contribution of lipid vs GTPase binding not separated here
   • Did not define the captured vesicle class
4. 2005 High

   Biophysical characterization established golgin-97 as an extended parallel coiled-coil homodimer, explaining how a single golgin presents a long tether without cross-pairing with other GRIP proteins.

   Evidence Co-IP, chemical cross-linking, yeast two-hybrid, and CD spectroscopy of recombinant protein

   PMID:15654769

   Open questions at the time

   • No full-length structure
   • Stoichiometry of dimer engagement with Arl1 not resolved
5. 2005 High

   The first specific cargo was identified, showing golgin-97 is not a generic tether but selectively required for E-cadherin export in TGN-derived tubulovesicular carriers.

   Evidence Live imaging of GFP-tagged carriers plus siRNA knockdown with E-cadherin trafficking readout

   PMID:16262725

   Open questions at the time

   • Mechanism linking golgin-97 to the E-cadherin carrier not defined
   • Direct vs indirect cargo selection unclear at this stage
6. 2006 High

   The molecular logic of GRIP targeting was resolved into a three-tier hierarchy (dimerization, bivalent Arl1-GTP binding, direct lipid contact), integrating the earlier mutagenesis and GTPase data into one mechanism.

   Evidence Mutational analysis of >30 GRIP mutants with SPR lipid binding and in vivo targeting assays

   PMID:16899086

   Open questions at the time

   • Lipid identity recognized by basic/hydrophobic residues not specified
   • Did not address N-terminal vesicle-capture function
7. 2006 Medium

   A non-canonical role emerged in poxvirus morphogenesis, where golgin-97 is rerouted to viral factories and required for mature virion formation.

   Evidence Immunofluorescence, virion fractionation, siRNA depletion and EM of virion morphology

   PMID:16987983 PMID:17276477

   Open questions at the time

   • Mechanism by which golgin-97 contributes to core maturation unknown
   • Relationship to its TGN tethering function unclear
8. 2010 Medium

   Identification of the Rab11 effector FIP1/RCP as a C-terminal partner provided a molecular link for tethering recycling-endosome-derived retrograde carriers, separate from the GRIP recruitment function.

   Evidence MS identification, co-IP, EM, and TGN38/Shiga toxin retrograde transport assays

   PMID:20610657

   Open questions at the time

   • Direct vs adaptor-mediated binding not fully resolved
   • Single lab, not reciprocally cross-validated against later TBC1D23 model
9. 2017 High

   The N-terminal capture motif and its adaptor were defined, showing a short tip region is necessary and sufficient to capture a specific endosome-derived carrier class via the bridging adaptor TBC1D23, which links the golgin tip to the WASH complex.

   Evidence Ectopic golgin relocation, N-terminal truncation mapping, BioID, co-IP and siRNA trafficking assays across multiple golgins

   PMID:28122620 PMID:29084197

   Open questions at the time

   • How TBC1D23 distinguishes correct vesicles at the molecular level not yet shown
   • Physiological cargo of these carriers not enumerated here
10. 2018 Medium

    Cargo selectivity was sharpened by positive and negative results: golgin-97 directly binds and exports Kir2.1, but is dispensable for retromer-dependent CI-M6PR retrograde transport, which uses GCC88.

    Evidence Golgi-tether screen with in vitro pull-downs and siRNA for Kir2.1; Vps35 knockout with EM golgin-marker tethering for CI-M6PR

    PMID:30123141 PMID:30559172

    Open questions at the time

    • Structural basis of Kir2.1 GRIP-domain binding not determined
    • Full cargo repertoire of golgin-97 vs sibling golgins incomplete
11. 2018 Medium

    A Golgi-independent signaling role was uncovered: golgin-97 suppresses NF-κB by maintaining IκBα, linking its loss to breast cancer invasion.

    Evidence siRNA knockdown/re-expression, fractionation, luciferase reporter and Western blot in breast cancer cells

    PMID:29703230

    Open questions at the time

    • Molecular mechanism by which golgin-97 stabilizes IκBα unknown
    • Direct binding partners in the NF-κB axis not identified
12. 2020 Medium

    Structural and stability mechanisms were added: the TBC1D23 rhodanese-TBC platform was shown to form the golgin-binding surface (catalytically inactive), and Arl1 was shown to be continuously required, as its oxidative degradation releases golgin-97 from the membrane.

    Evidence X-ray crystallography with zebrafish neurodevelopment assay; H2O2 treatment with NAC/protease-inhibitor rescue and transport assays

    PMID:32453802 PMID:32583744

    Open questions at the time

    • Whether oxidative regulation of golgin-97 occurs physiologically not established
    • Functional consequence of golgin-97 binding in neurodevelopment via TBC1D23 vs golgin-97 itself not separated
13. 2022 High

    A post-translational regulatory layer was defined: PKD-activated PARP12 mono-ADP-ribosylates an acidic cluster in golgin-97's coiled-coil, gating carrier fission and E-cadherin/VSVG export.

    Evidence In vitro ADP-ribosylation, acidic-cluster mutagenesis, siRNA, live-cell cargo imaging and co-IP

    PMID:34969853

    Open questions at the time

    • How the modification mechanically drives carrier fission unknown
    • Why golgin-245-dependent cargo is exempt not explained
14. 2024 High

    Cargo recognition at the carrier level was resolved structurally: TBC1D23's C-terminal domain directly reads an acidic TLY motif on endosome-to-Golgi cargoes, completing the chain from golgin tip to specific cargo.

    Evidence Protein binding assays, X-ray crystallography of TBC1D23-CTD bound to the TLY motif, and structure-guided mutagenesis with in vivo capture assay

    PMID:38552021

    Open questions at the time

    • Generality of the TLY code across the full cargo set not exhaustively mapped
    • How motif recognition is coordinated with WASH-complex binding not resolved

• It remains unknown how golgin-97's distinct activities—TGN vesicle tethering, selective basolateral cargo export, and Golgi-independent NF-κB suppression—are integrated and switched within a single cell, and whether the protein has a defined Mendelian disease association.
• No structural model of full-length dimer engaging Arl1 and a vesicle simultaneously
• Mechanism of cytosolic golgin-97 pool and its NF-κB function uncharacterized
• No direct evidence linking GOLGA1 to a human disease in the corpus