Secretory carrier-associated membrane protein 2 (SCAMP2) is a tetraspanning integral membrane protein belonging to the SCAMP family. It functions as a regulator of membrane trafficking in post-Golgi recycling pathways, shuttling between the trans-Golgi network (TGN), recycling endosomes, and the plasma membrane. SCAMP2 directly interacts with and regulates the subcellular distribution and cell-surface targeting of membrane transport proteins including Na+/H+ exchangers (NHE5, NHE7) and the serotonin transporter (SERT). The protein contains cytosolic N- and C-termini with NPF repeats and proline-rich sequences that may mediate interactions with SH3/WW-domain proteins, and a conserved cytoplasmic loop between TM2-TM3 that is critical for cargo binding. SCAMP2 promotes surface targeting of NHE5 through an Arf6-dependent mechanism and participates in the redistribution of cargo proteins between recycling vesicles and the TGN.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0006887 exocytosis | IBA GO_REF:0000033 | ACCEPT | Summary: IBA annotation based on phylogenetic inference. SCAMP family proteins are implicated in regulated exocytosis based on their localization to secretory vesicles and functional studies showing roles in late steps of exocytosis (PMID:9378760, Hubbard et al. 2000). Reason: The annotation to exocytosis is well-supported by the known role of SCAMP proteins in secretory and endocytic membrane trafficking. SCAMPs are enriched on secretory granules and recycling carriers, and family-level studies support roles in regulated exocytosis. The IBA annotation is consistent with SCAMP2's documented functions in post-Golgi vesicle-mediated transport. Supporting Evidence: PMID:9378760 SCAMPs may largely function at the same sites during vesicular transport rather than in separate post-Golgi recycling pathways. file:human/SCAMP2/SCAMP2-deep-research-falcon.md SCAMP family proteins, including SCAMP2, are implicated in the regulation of membrane trafficking steps that govern exocytosis and endocytosis/recycling |
| GO:0032588 trans-Golgi network membrane | IBA GO_REF:0000033 | ACCEPT | Summary: IBA annotation for TGN membrane localization. This is strongly supported by experimental evidence from PMID:15840657 showing SCAMP2 accumulation at the TGN. Reason: TGN membrane localization is experimentally validated. Lin et al. showed that the majority of NHE7-SCAMP complexes accumulated at the TGN and SCAMP2 is involved in shuttling cargo between recycling vesicles and the TGN. Supporting Evidence: PMID:15840657 The majority of the NHE7-SCAMP complexes accumulated at the TGN, but a minor fraction also resided in recycling vesicles. |
| GO:0055038 recycling endosome membrane | IBA GO_REF:0000033 | ACCEPT | Summary: IBA annotation for recycling endosome membrane localization. This is experimentally validated by studies showing SCAMP2 localizes to recycling endosomes and regulates cargo transit through this compartment. Reason: Recycling endosome localization is well-supported experimentally. Multiple studies demonstrate SCAMP2 in recycling endosomes where it regulates trafficking of NHE5 and NHE7. Supporting Evidence: PMID:15840657 The majority of the NHE7-SCAMP complexes accumulated at the TGN, but a minor fraction also resided in recycling vesicles. PMID:19276089 secretory carrier membrane proteins (SCAMPs), a group of tetraspanning integral membrane proteins that reside in multiple secretory and endocytic organelles, bind to NHE5 and co-localize predominantly in the recycling endosomes. |
| GO:0005794 Golgi apparatus | IEA GO_REF:0000044 | ACCEPT | Summary: IEA annotation based on UniProt subcellular location mapping. This is a broader term that encompasses the experimentally validated TGN localization. Reason: The Golgi apparatus annotation is correct but less specific than trans-Golgi network membrane. Given that TGN-specific annotations also exist, this broader annotation remains acceptable as it is not incorrect, just less informative. Supporting Evidence: PMID:15840657 The majority of the NHE7-SCAMP complexes accumulated at the TGN |
| GO:0015031 protein transport | IEA GO_REF:0000120 | ACCEPT | Summary: IEA annotation for protein transport based on InterPro domain mapping. SCAMP2 regulates the trafficking and cell-surface targeting of cargo proteins including Na+/H+ exchangers and the serotonin transporter. Reason: Protein transport is a well-supported function of SCAMP2. Multiple studies demonstrate its role in regulating subcellular distribution and trafficking of membrane transporters such as NHE5, NHE7, and SERT. Supporting Evidence: PMID:15840657 We propose a model wherein SCAMPs participate in the shuttling of NHE7 between recycling vesicles and the TGN. PMID:19276089 SCAMP2 regulates NHE5 transit through recycling endosomes and promotes its surface targeting in an Arf6-dependent manner. |
| GO:0016020 membrane | IEA GO_REF:0000002 | ACCEPT | Summary: IEA annotation for membrane localization based on InterPro domain. SCAMP2 is an integral membrane protein with four transmembrane helices. Reason: Membrane localization is fundamental to SCAMP2 function. It is a tetraspanning integral membrane protein. This annotation is correct but very broad - more specific membrane annotations (TGN membrane, recycling endosome membrane) also exist. Supporting Evidence: PMID:9378760 The primary structures of three human forms of secretory carrier membrane proteins (SCAMPs) have been deduced |
| GO:0055038 recycling endosome membrane | IEA GO_REF:0000044 | ACCEPT | Summary: Duplicate IEA annotation for recycling endosome membrane based on UniProt subcellular location mapping. Same term as the IBA annotation above. Reason: Duplicate annotation with different evidence code. The recycling endosome membrane localization is experimentally validated and correctly annotated by multiple sources. Supporting Evidence: PMID:19276089 secretory carrier membrane proteins (SCAMPs)...bind to NHE5 and co-localize predominantly in the recycling endosomes. |
| GO:0005515 protein binding | IPI PMID:15840657 Secretory carrier membrane proteins interact and regulate tr... | MODIFY | Summary: IPI annotation for protein binding based on interaction with SLC9A7 (NHE7). The study used yeast two-hybrid, co-immunoprecipitation, and in vitro binding assays to demonstrate direct interaction. Reason: While the interaction with NHE7 is well-documented, 'protein binding' is too generic and uninformative. SCAMP2 functions as a trafficking regulator for NHE7, not just a binding partner. A more specific molecular function term describing its role in binding transmembrane transporters would be more appropriate. Proposed replacements: transmembrane transporter binding Supporting Evidence: PMID:15840657 Direct association of these two proteins was further supported by co-immunolocalization and co-immunoprecipitation analyses using transfected cells, by their co-sedimentation in membrane fractions resolved on sucrose density gradients, and by in vitro protein binding assays. |
| GO:0005515 protein binding | IPI PMID:32296183 A reference map of the human binary protein interactome. | MARK AS OVER ANNOTATED | Summary: IPI annotation for protein binding based on HuRI (Human Reference Interactome) systematic Y2H screening identifying interaction with SLC41A1. Reason: High-throughput interactome study (HuRI) detecting binary interactions. While technically correct that SCAMP2 binds proteins, this annotation from large-scale Y2H screening adds no specific functional information. The interaction with SLC41A1 has not been validated in the context of SCAMP2's trafficking function. Supporting Evidence: PMID:32296183 Here we present a human 'all-by-all' reference interactome map of human binary protein interactions, or 'HuRI'. With approximately 53,000 protein-protein interactions |
| GO:0005515 protein binding | IPI PMID:32814053 Interactome Mapping Provides a Network of Neurodegenerative ... | MARK AS OVER ANNOTATED | Summary: IPI annotation for protein binding based on neurodegenerative disease interactome mapping study identifying interaction with FLNA (filamin A). Reason: High-throughput interactome screening in the context of neurodegenerative disease. SCAMP2 is not a core neurodegenerative disease protein, and the interaction with FLNA lacks functional validation in the context of SCAMP2's known trafficking roles. The generic 'protein binding' annotation provides no functional insight. Supporting Evidence: PMID:32814053 Interactome Mapping Provides a Network of Neurodegenerative Disease Proteins and Uncovers Widespread Protein Aggregation in Affected Brains |
| GO:0005794 Golgi apparatus | IDA GO_REF:0000052 | ACCEPT | Summary: IDA annotation for Golgi apparatus localization based on HPA immunofluorescence curation. Consistent with the experimental literature showing TGN localization. Reason: Golgi apparatus localization is experimentally validated by multiple approaches including immunofluorescence. This is consistent with SCAMP2's role in post-Golgi trafficking. Supporting Evidence: PMID:15840657 The majority of the NHE7-SCAMP complexes accumulated at the TGN |
| GO:0005515 protein binding | IPI PMID:19276089 Secretory Carrier Membrane Protein 2 Regulates Cell-surface ... | MODIFY | Summary: IPI annotation for protein binding based on interaction with SLC9A5 (NHE5). The study demonstrated direct binding and functional regulation of NHE5 cell-surface targeting by SCAMP2. Reason: The interaction with NHE5 is functionally characterized - SCAMP2 regulates NHE5 cell-surface targeting in an Arf6-dependent manner. Generic 'protein binding' fails to capture this regulatory function. A more specific term would be preferable. Proposed replacements: transmembrane transporter binding Supporting Evidence: PMID:19276089 In vitro protein-protein interaction assays revealed that NHE5 directly binds to the N- and C-terminal cytosolic extensions of SCAMP2. Heterologous expression of SCAMP2 but not SCAMP5 increased cell-surface abundance as well as transporter activity of NHE5 across the plasma membrane. |
| GO:0070062 extracellular exosome | HDA PMID:20458337 MHC class II-associated proteins in B-cell exosomes and pote... | KEEP AS NON CORE | Summary: HDA annotation for extracellular exosome localization based on mass spectrometry proteomics of B-cell exosomes. SCAMP2 was identified in the exosome proteome but not among the MHC class II-associated proteins of specific interest. Reason: Detection in exosome proteomics is consistent with SCAMP2's role in membrane trafficking and recycling. However, exosome localization is likely a secondary consequence of its primary function in endosomal/TGN trafficking rather than a core function. The study did not specifically focus on SCAMP2 function in exosomes. Supporting Evidence: PMID:20458337 we first analyzed the total proteome of highly purified B cell-derived exosomes using sensitive and accurate mass spectrometry (MS), and identified 539 proteins |
| GO:0005515 protein binding | IPI PMID:16870614 Subcellular redistribution of the serotonin transporter by s... | MODIFY | Summary: IPI annotation for protein binding based on interaction with SLC6A4 (SERT, serotonin transporter). The study demonstrated direct interaction and functional regulation of SERT subcellular distribution by SCAMP2. Reason: SCAMP2 interaction with SERT is functionally characterized - it causes subcellular redistribution with decreased cell surface SERT and reduced 5-HT uptake. Generic 'protein binding' fails to capture this regulatory relationship. Proposed replacements: transmembrane transporter binding Supporting Evidence: PMID:16870614 GST-pulldown assays confirmed the physical interaction between SCAMP2 and the N-terminal domain of SERT...Co-expression of SERT and SCAMP2 in mammalian cells results in the subcellular redistribution of SERT with a decrease in cell surface SERT and a concomitant reduction in 5-HT uptake activity. |
| GO:0015031 protein transport | IDA PMID:15840657 Secretory carrier membrane proteins interact and regulate tr... | ACCEPT | Summary: IDA annotation for protein transport based on experimental evidence showing SCAMP2 regulates trafficking of NHE7 between recycling vesicles and the TGN. Reason: This is a core function of SCAMP2 supported by experimental evidence demonstrating its role in shuttling NHE7 between compartments and regulating cargo protein distribution. Supporting Evidence: PMID:15840657 We propose a model wherein SCAMPs participate in the shuttling of NHE7 between recycling vesicles and the TGN. |
| GO:0016020 membrane | IDA PMID:15840657 Secretory carrier membrane proteins interact and regulate tr... | ACCEPT | Summary: IDA annotation for membrane localization based on experimental evidence from fractionation and microscopy studies. Reason: Membrane localization is fundamental to SCAMP2 as a tetraspanning integral membrane protein. The annotation is correct though very broad. Supporting Evidence: PMID:15840657 by their co-sedimentation in membrane fractions resolved on sucrose density gradients |
| GO:0032588 trans-Golgi network membrane | IDA PMID:15840657 Secretory carrier membrane proteins interact and regulate tr... | ACCEPT | Summary: IDA annotation for TGN membrane localization based on direct experimental observation of SCAMP2-NHE7 complex accumulation at the TGN. Reason: TGN membrane localization is a core feature of SCAMP2 function, representing a major site where it regulates cargo trafficking. Supporting Evidence: PMID:15840657 The majority of the NHE7-SCAMP complexes accumulated at the TGN, but a minor fraction also resided in recycling vesicles. |
| GO:0055038 recycling endosome membrane | IDA PMID:15840657 Secretory carrier membrane proteins interact and regulate tr... | ACCEPT | Summary: IDA annotation for recycling endosome membrane localization based on experimental evidence showing SCAMP2 in recycling vesicles. Reason: Recycling endosome membrane localization is a core feature of SCAMP2 function, representing a compartment where it regulates cargo protein transit. Supporting Evidence: PMID:15840657 The majority of the NHE7-SCAMP complexes accumulated at the TGN, but a minor fraction also resided in recycling vesicles. PMID:19276089 SCAMP2 regulates NHE5 transit through recycling endosomes and promotes its surface targeting |
| GO:0006892 post-Golgi vesicle-mediated transport | TAS PMID:9378760 Three mammalian SCAMPs (secretory carrier membrane proteins)... | ACCEPT | Summary: TAS annotation for post-Golgi vesicle-mediated transport based on the foundational SCAMP characterization paper describing their role in post-Golgi recycling pathways. Reason: This is a core biological process for SCAMP2. The annotation accurately captures its role in shuttling cargo between the TGN and recycling compartments. Supporting Evidence: PMID:9378760 These findings suggest that the SCAMPs may largely function at the same sites during vesicular transport rather than in separate post-Golgi recycling pathways. |
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Download this section (compressed HTML)Q: Does SCAMP2 have a specific molecular function term that captures its role as a trafficking regulator for membrane transporters, beyond generic 'protein binding'? Multiple studies show SCAMP2 physically interacts with and functionally regulates the subcellular distribution of cargo proteins, but current MF annotations are limited to the uninformative 'protein binding' term.
Experiment: Identify the full repertoire of SCAMP2 cargo proteins beyond NHE5, NHE7, and SERT using proximity labeling (BioID/TurboID) followed by mass spectrometry. Current knowledge of SCAMP2 cargo is limited to a few transporters. A comprehensive cargo identification would better define its functional scope.
Hypothesis: SCAMP2 regulates trafficking of additional membrane transporters beyond the currently characterized NHE5, NHE7, and SERT.
Experiment: Characterize the structural basis of SCAMP2-cargo interactions using cryo-EM or crystallography of SCAMP2 TM2-TM3 loop with cargo cytoplasmic domains. The TM2-TM3 loop is critical for cargo binding but the molecular details of recognition are unknown.
Hypothesis: The TM2-TM3 cytoplasmic loop of SCAMP2 contains a conserved binding interface that recognizes specific motifs in cargo protein cytoplasmic tails.
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