Affinage

GEMIN7

Gem-associated protein 7 · UniProt Q9H840

Length
131 aa
Mass
14.5 kDa
Annotated
2026-04-28
15 papers in source corpus 12 papers cited in narrative 11 extracted findings

Mechanistic narrative

Synthesis pass · prose summary of the discoveries below

GEMIN7 is a core structural component of the SMN complex that functions in the cytoplasmic assembly of spliceosomal snRNPs. Despite lacking sequence similarity to Sm proteins, GEMIN7 adopts a canonical Sm fold and forms a stable heterodimer with GEMIN6 through an Sm-protein-like interface; this heterodimer acts as a surrogate for the SmD3–SmB particle and is exchanged by SmD3–SmB during Sm ring closure, a process facilitated by Unrip (PMID:15939020, PMID:19321448). GEMIN7 directly binds SMN via its arginine-glycine repeats, interacts with GEMIN2 and SmE, and recruits Unrip to form a stable GEMIN6–GEMIN7–Unrip submodule that is bridged to SMN by GEMIN8 (PMID:12065586, PMID:16434402, PMID:17178713). Beyond snRNP biogenesis, the GEMIN7-containing SMN complex localizes to neuronal transport granules in axons, where it partitions into stationary and motile populations (PMID:15975577, PMID:20188701).

Mechanistic history

Synthesis pass · year-by-year structured walk · 8 steps
  1. 2002 High

    Identification of GEMIN7 as a novel SMN-complex component that directly contacts SMN, GEMIN6, and Sm proteins established it as a previously unrecognized participant in the snRNP assembly machinery.

    Evidence Native SMN complex purification, mass spectrometry, reciprocal co-IP, direct binding assays, and RG-repeat mutagenesis in human cells

    PMID:12065586

    Open questions at the time
    • Structural basis of the GEMIN7–SMN interaction unresolved
    • No functional assay for snRNP assembly performed at this stage
  2. 2005 High

    The crystal structure of the GEMIN6–GEMIN7 heterodimer revealed that both adopt Sm folds and interact through an Sm-like interface, explaining how they can bind Sm proteins and suggesting they template Sm ring organization.

    Evidence X-ray crystallography of the GEMIN6–GEMIN7 complex with in vitro Sm-protein binding validation

    PMID:15939020

    Open questions at the time
    • How the heterodimer is positioned relative to the Sm ring during assembly was not resolved
    • No full-complex structural model available
  3. 2005 High

    Discovery that Unrip is recruited to the SMN complex through direct binding to GEMIN7 and that this interaction regulates SMN nuclear-cytoplasmic distribution linked GEMIN7 to a regulatory axis controlling SMN complex localization.

    Evidence Co-IP, RNAi knockdown of Unrip with immunofluorescence readout of gems/Cajal bodies in HeLa cells; confirmed across two independent labs

    PMID:15848170 PMID:16159890

    Open questions at the time
    • Molecular basis of Unrip-mediated retention of SMN in the cytoplasm unknown
    • Whether Unrip regulation is relevant in motor neurons specifically not tested
  4. 2006 High

    Reconstitution of the SMN complex from individual components demonstrated that GEMIN7, together with SMN and GEMIN8, constitutes a core architectural scaffold, with GEMIN8 bridging the GEMIN6/7 heterodimer to SMN.

    Evidence In vitro complex reconstitution from purified components, RNAi epistasis, and direct binding assays

    PMID:16434402 PMID:17023415 PMID:17178713

    Open questions at the time
    • Whether GEMIN8 loss completely abolishes GEMIN7 function or only reduces efficiency unclear
    • Stoichiometry of GEMIN7 within the native complex not determined
  5. 2007 Medium

    Demonstration that the GEMIN6–GEMIN7–Unrip subcomplex persists independently of SMN levels established it as a pre-formed module that is recruited en bloc to the assembly machinery.

    Evidence Sedimentation analysis and immunoprecipitation from SMN-depleted cell extracts

    PMID:17640873

    Open questions at the time
    • Functional consequence of the free subcomplex (beyond snRNP assembly) not explored
    • Single-lab observation without independent replication
  6. 2009 High

    Identification of a GEMIN2–GEMIN7 direct interaction and the finding that the GEMIN6–GEMIN7 heterodimer is displaced by SmD3–SmB during ring closure revealed the mechanistic logic: GEMIN6/7 acts as a SmD3/SmB surrogate that is exchanged to complete the Sm ring.

    Evidence Mammalian two-hybrid, in vitro displacement assays, GEMIN7 RNAi with snRNP assembly and SmE incorporation readouts

    PMID:19321448

    Open questions at the time
    • Kinetics and order of the exchange reaction not defined
    • Whether Unrip actively catalyzes the exchange or merely permits it is unresolved
  7. 2010 Medium

    Live-cell imaging of GFP-GEMIN7 in neurons showed SMN-containing granules partition into stationary and motile populations in neurites, extending GEMIN7's functional context beyond snRNP assembly to neuronal RNA transport.

    Evidence Live-cell fluorescence imaging of GFP-GEMIN7 in differentiated neuronal cells and PC12 cells

    PMID:15975577 PMID:20188701

    Open questions at the time
    • No direct manipulation of GEMIN7 in neuronal transport assays
    • Cargo identity of motile GEMIN7-positive granules unknown
  8. 2017 Medium

    Conservation of the GEMIN6/7/Unrip module in Drosophila, recruited to the SMN complex via GEMIN8, confirmed that this architectural arrangement is an ancient feature of the snRNP assembly pathway.

    Evidence Co-immunoprecipitation of Drosophila orthologs in vivo

    PMID:28949413

    Open questions at the time
    • Functional snRNP assembly assay not performed in Drosophila for GEMIN7 specifically
    • Whether invertebrate GEMIN7 retains the SmD3/SmB surrogate exchange mechanism untested

Open questions

Synthesis pass · forward-looking unresolved questions
  • How the GEMIN6–GEMIN7 heterodimer is spatially positioned within the full SMN complex during the Sm-ring closure reaction, the precise kinetics and regulation of the SmD3–SmB exchange, and the functional significance of GEMIN7 in neuronal granule transport remain unresolved.
  • No high-resolution structure of the full SMN complex including GEMIN7 in the act of Sm ring loading
  • No in vivo GEMIN7-specific loss-of-function studies in neurons
  • Role of GEMIN7 post-translational modifications (e.g., RG-repeat methylation) unexplored

Mechanism profile

Synthesis pass · controlled-vocabulary classification · explore literature graph →
Molecular activity
GO:0005198 structural molecule activity 3 GO:0060090 molecular adaptor activity 3
Localization
GO:0005829 cytosol 2 GO:0005856 cytoskeleton 2 GO:0005634 nucleus 1
Pathway
R-HSA-8953854 Metabolism of RNA 4
Partners
GEMIN2GEMIN6GEMIN8SMNSNRPEUNRIP
Complex memberships
Gemin6-Gemin7-Unrip subcomplexSMN complex

Evidence

Reading pass · 11 per-paper findings extracted from the source corpus
Year Finding Method Journal Conf PMIDs
2002 Gemin7 was identified as a novel component of the SMN complex; it interacts directly with SMN and Gemin6, mediates the association of Gemin6 with the SMN complex, and interacts with several Sm proteins (particularly SmE). The arginine-glycine repeats in Gemin7 are necessary for its interaction with SMN. Native purification of SMN complexes, peptide sequencing by mass spectrometry, co-immunoprecipitation, immunolocalization, and direct binding experiments The Journal of biological chemistry High 12065586
2005 Crystal structure of the Gemin6-Gemin7 heterodimer revealed that both proteins adopt canonical Sm folds despite lacking sequence similarity to Sm proteins, and they interact with each other via an Sm-protein-like interface. The Gemin6/Gemin7 complex binds to Sm proteins, suggesting a role in organizing Sm proteins for snRNA ring formation. X-ray crystallography and in vitro binding experiments Structure High 15939020
2005 Unrip is recruited to the SMN complex via a stable, direct interaction with Gemin7. This interaction is mutually exclusive with unrip's association with the unr protein complex, and RNAi-mediated reduction of unrip leads to enhanced nuclear accumulation of SMN (increased gems/Cajal bodies), demonstrating that the Gemin7-unrip interaction influences intracellular distribution of the SMN complex. Co-immunoprecipitation, RNAi knockdown, immunofluorescence microscopy Human molecular genetics High 15848170 16159890
2005 Unrip directly interacts with both Gemin6 and Gemin7, and unrip-containing SMN complexes are necessary and sufficient to mediate spliceosomal snRNP assembly in vitro. Co-immunoprecipitation, in vitro snRNP assembly assay FEBS letters High 15848170
2006 Gemin7 is a central building block of the SMN complex architecture together with SMN and Gemin8; the SMN complex can be reconstituted from individual components and Gemin7 is among the core components onto which peripheral components are assembled via multiple interactions. In vivo and in vitro binding assays, reconstitution of SMN complex from individual components The Journal of biological chemistry High 17178713
2006 Gemin6, Gemin7, and Unrip form a stable cytoplasmic heteromeric subunit of the SMN complex; Gemin8 directly binds SMN and mediates the interaction of SMN with the Gemin6/Gemin7 heterodimer. Loss of Gemin8 disrupts the Gemin6/Gemin7/Unrip–SMN interaction, impairing Sm protein recruitment to the snRNP assembly pathway without affecting snRNA binding. Co-immunoprecipitation with monoclonal antibodies, RNA interference, in vitro binding assays The Journal of biological chemistry High 16434402 17023415
2007 Gemin6, Gemin7, and Unrip form a stable SMN-independent subcomplex that persists even when SMN levels are reduced. This subcomplex participates in snRNP assembly as a distinct module within the SMN complex. Sedimentation analysis, immunoprecipitation from cell extracts The Journal of biological chemistry Medium 17640873
2009 Gemin2 directly interacts with Gemin7 (identified by mammalian two-hybrid), stabilizing the SMN-Gemin7 interaction. Gemin7 knockdown reduces snRNP assembly activity and decreases SmE in the SMN complex. Unrip (but not Gemin8) can displace Gemin7 from the SMN-Gemin2-Gemin7 ternary complex, suggesting the Gemin6-Gemin7 heterodimer acts as a surrogate for the SmD3-SmB particle and is exchanged by SmD3-SmB during snRNP formation. Mammalian two-hybrid, in vitro stability assay, RNAi knockdown of Gemin7 and Unrip, in vitro snRNP assembly assay The Journal of biological chemistry High 19321448
2005 Gemin7 (along with SMN, Gemin2, Gemin6, and Unrip) localizes to neurite-like cytoplasmic extensions and growth cones of differentiating PC12 cells, suggesting SMN complexes containing Gemin7 participate in axonal transport of mRNPs. Immunofluorescence colocalization in differentiating PC12 cells Experimental cell research Medium 15975577
2010 Live-cell imaging of GFP-Gemin7 in neuronal cells revealed that SMN-Gemin complexes localize to two distinct subsets of neurite granules: stationary bodies and smaller dynamic (motile) bodies, and that SMN granules appear metamorphic in composition. Live-cell fluorescence imaging of GFP-tagged Gemin7 in neuronal cells Biochemical and biophysical research communications Medium 20188701
2017 In Drosophila, the Gemin6/7/Unrip module can be recruited to the SMN complex via a Gemin8 orthologue, mirroring the human SMN complex architecture and confirming the conserved role of Gemin7 in this modular subunit. In vivo interaction assays in Drosophila (co-immunoprecipitation) FEBS letters Medium 28949413

Source papers

Stage 0 corpus · 15 papers · ranked by NIH iCite citations
Year Title Journal Citations PMID
2006 A comprehensive interaction map of the human survival of motor neuron (SMN) complex. The Journal of biological chemistry 120 17178713
2005 A role for complexes of survival of motor neurons (SMN) protein with gemins and profilin in neurite-like cytoplasmic extensions of cultured nerve cells. Experimental cell research 110 15975577
2002 Identification and characterization of Gemin7, a novel component of the survival of motor neuron complex. The Journal of biological chemistry 92 12065586
2006 Gemin8 is a novel component of the survival motor neuron complex and functions in small nuclear ribonucleoprotein assembly. The Journal of biological chemistry 87 16434402
2005 Unrip, a factor implicated in cap-independent translation, associates with the cytosolic SMN complex and influences its intracellular localization. Human molecular genetics 70 16159890
2005 Unrip is a component of SMN complexes active in snRNP assembly. FEBS letters 66 15848170
2007 SMN-independent subunits of the SMN complex. Identification of a small nuclear ribonucleoprotein assembly intermediate. The Journal of biological chemistry 55 17640873
2006 Gemin8 is required for the architecture and function of the survival motor neuron complex. The Journal of biological chemistry 49 17023415
2005 The Gemin6-Gemin7 heterodimer from the survival of motor neurons complex has an Sm protein-like structure. Structure (London, England : 1993) 43 15939020
2003 The contribution of genetic and epigenetic mechanisms to gene silencing in oligodendrogliomas. Cancer research 36 14633674
2010 Analysis of SMN-neurite granules: Core Cajal body components are absent from SMN-cytoplasmic complexes. Biochemical and biophysical research communications 24 20515655
2009 Role of survival motor neuron complex components in small nuclear ribonucleoprotein assembly. The Journal of biological chemistry 21 19321448
2010 SMN and the Gemin proteins form sub-complexes that localise to both stationary and dynamic neurite granules. Biochemical and biophysical research communications 20 20188701
2017 Novel interactors of the Drosophila Survival Motor Neuron (SMN) Complex suggest its full conservation. FEBS letters 17 28949413
2018 Sporadic amyotrophic lateral sclerosis: is SMN-Gemins protein complex of importance for the relative resistance of oculomotor nucleus motoneurons to degeneration? Folia neuropathologica 0 30786668