SRP68

Existing Annotations Review

GO Term	Evidence	Action	Reason
GO:0006614 SRP-dependent cotranslational protein targeting to membrane	IBA GO_REF:0000033	ACCEPT	Summary: SRP68 is a core SRP subunit and participates directly in SRP-dependent cotranslational targeting of secretory and membrane proteins to the ER. This is the defining biological process of the gene and is conserved across the SRP68 family. Reason: Phylogenetically (IBA) and experimentally supported core biological process; SRP68 is an essential S-domain subunit of the targeting SRP complex. Supporting Evidence: file:human/SRP68/SRP68-uniprot.txt a ribonucleoprotein complex that mediates the cotranslational targeting of secretory and membrane proteins to the endoplasmic reticulum (ER)
GO:0005047 signal recognition particle binding	IBA GO_REF:0000033	ACCEPT	Summary: SRP68 binds within the SRP complex, contacting the 7SL RNA and the SRP72/SRP19 components; signal recognition particle binding captures its integral association with the particle. Reason: Core molecular function corroborated by structural and biochemical evidence of SRP68 binding SRP RNA and SRP72 within the particle. Supporting Evidence: file:human/SRP68/SRP68-uniprot.txt Binds the signal recognition particle RNA (7SL RNA), SRP72 binds to this complex subsequently
GO:0005786 signal recognition particle, endoplasmic reticulum targeting	IBA GO_REF:0000033	ACCEPT	Summary: SRP68 is a constitutive subunit of the ER-targeting signal recognition particle. Conserved across the family. Reason: Core cellular component; SRP68 is one of the six defining SRP protein subunits. Supporting Evidence: file:human/SRP68/SRP68-uniprot.txt Component of a signal recognition particle (SRP) complex that consists of a 7SL RNA molecule of 300 nucleotides and six protein subunits: SRP72, SRP68, SRP54, SRP19, SRP14 and SRP9
GO:0003723 RNA binding	IEA GO_REF:0000002	ACCEPT	Summary: SRP68 binds the SRP (7SL) RNA via its N-terminal RNA-binding domain; the general RNA binding term is a correct parent of the more specific 7S RNA binding. Reason: Correct general molecular function; the more precise GO:0008312 (7S RNA binding) better captures the specific activity. Supporting Evidence: file:human/SRP68/SRP68-uniprot.txt The N-terminus is required for RNA-binding.
GO:0005047 signal recognition particle binding	IEA GO_REF:0000002	ACCEPT	Summary: InterPro-based electronic assignment of signal recognition particle binding, consistent with the experimental/IBA evidence. Reason: Correct core molecular function; redundant with IBA and IPI evidence. Supporting Evidence: file:human/SRP68/SRP68-uniprot.txt Binds the signal recognition particle RNA (7SL RNA), SRP72 binds to this complex subsequently
GO:0005730 nucleolus	IEA GO_REF:0000044	KEEP AS NON CORE	Summary: A pool of SRP68 traffics through the nucleolus, consistent with partial SRP assembly there; this is not its core site of action. Reason: Real localization (UniProt subcellular location; PMID:10618370) reflecting SRP assembly trafficking, not the core cytosolic/ER targeting function. Supporting Evidence: file:human/SRP68/SRP68-uniprot.txt Nucleus, nucleolus PMID:10618370 green fluorescent protein fusions of SRP19, SRP68, and SRP72 localized to the nucleolus, as well as to the cytoplasm
GO:0005737 cytoplasm	IEA GO_REF:0000044	ACCEPT	Summary: SRP68 is predominantly cytoplasmic, consistent with the cytosolic SRP targeting cycle. Reason: Correct compartment; SRP acts in the cytoplasm to capture nascent chains on translating ribosomes. Supporting Evidence: file:human/SRP68/SRP68-uniprot.txt SUBCELLULAR LOCATION: Cytoplasm
GO:0005783 endoplasmic reticulum	IEA GO_REF:0000044	ACCEPT	Summary: SRP68 accumulates at the ER, consistent with delivery of the SRP-ribosome-nascent chain complex to the ER-bound SRP receptor. Reason: Correct; ER association reflects the targeting endpoint where SRP docks the nascent-chain complex. Supporting Evidence: file:human/SRP68/SRP68-uniprot.txt Endoplasmic reticulum {ECO:0000269\|PubMed:28369529}
GO:0005786 signal recognition particle, endoplasmic reticulum targeting	IEA GO_REF:0000002	ACCEPT	Summary: InterPro-based electronic assignment to the ER-targeting SRP, consistent with experimental evidence. Reason: Correct core cellular component; redundant with IBA/IDA. Supporting Evidence: file:human/SRP68/SRP68-uniprot.txt Component of a signal recognition particle (SRP) complex
GO:0005829 cytosol	IEA GO_REF:0000117	ACCEPT	Summary: Cytosolic localization consistent with the cytoplasmic SRP targeting cycle. Reason: Correct compartment; redundant with the IDA cytosol annotation and the UniProt cytoplasm location. Supporting Evidence: file:human/SRP68/SRP68-uniprot.txt SUBCELLULAR LOCATION: Cytoplasm
GO:0006614 SRP-dependent cotranslational protein targeting to membrane	IEA GO_REF:0000002	ACCEPT	Summary: Electronic (InterPro) assignment of the defining SRP cotranslational targeting process, consistent with IBA/NAS evidence. Reason: Correct core biological process; redundant with experimentally supported annotations. Supporting Evidence: file:human/SRP68/SRP68-uniprot.txt mediates the cotranslational targeting of secretory and membrane proteins to the endoplasmic reticulum
GO:0008312 7S RNA binding	IEA GO_REF:0000002	ACCEPT	Summary: SRP68 directly binds the 7SL (7S) SRP RNA through its N-terminal RNA-binding domain and remodels it; 7S RNA binding is the core molecular function. Reason: Core molecular function with structural support (crystal structures of SRP68-RBD with SRP RNA); also supported by IMP. Supporting Evidence: file:human/SRP68/SRP68-uniprot.txt Binds the signal recognition particle RNA (7SL RNA) PMID:24700861 We present the crystal structures of the RNA-binding domain of SRP68 (SRP68-RBD) alone and in complex with SRP RNA and SRP19.
GO:0030942 endoplasmic reticulum signal sequence receptor activity	IEA GO_REF:0000002	MARK AS OVER ANNOTATED	Summary: This activity describes the ER signal-sequence receptor (the SRP receptor / TRAP-type signal sequence receptor), not the 7SL-RNA-binding SRP68 scaffold subunit. The InterPro mapping over-extends a receptor function onto an SRP S-domain protein. Reason: SRP68 is an RNA-binding scaffold subunit of the cytosolic SRP, not a membrane signal-sequence receptor; signal-sequence receptor activity belongs to the SRP receptor (SRPR/SRPRB) and the SSR/TRAP complex, not to SRP68. Supporting Evidence: file:human/SRP68/SRP68-uniprot.txt The N-terminus is required for RNA-binding.
GO:0005515 protein binding	IPI PMID:16672232 Protein SRP68 of human signal recognition particle: identifi...	KEEP AS NON CORE	Summary: SRP68 binds SRP72 (and SRP RNA); this captures the SRP68-SRP72 heterodimer interaction. The informative aspect (SRP/SRP72 binding) is better represented by signal recognition particle binding; bare protein binding is uninformative. Reason: Records the real SRP68-SRP72 interaction but the bare protein binding term is uninformative; the SRP-binding function is captured by GO:0005047. Supporting Evidence: PMID:16672232 Human SRP68 was purified from overexpressing Escherichia coli cells and was found to bind to recombinant SRP72
GO:0005515 protein binding	IPI PMID:24700861 SRP RNA remodeling by SRP68 explains its role in protein tra...	KEEP AS NON CORE	Summary: Structural study of SRP68-RBD in complex with SRP19 and SRP RNA; the interaction captured is with SRP partners. Bare protein binding is uninformative. Reason: Real interaction within SRP (SRP19/RNA) but bare protein binding is uninformative; SRP function is captured by other terms. Supporting Evidence: PMID:24700861 in complex with SRP RNA and SRP19
GO:0005515 protein binding	IPI PMID:33961781 Dual proteome-scale networks reveal cell-specific remodeling...	KEEP AS NON CORE	Summary: High-throughput interactome (BioPlex) capture; bare protein binding is uninformative for core function. Reason: High-throughput interactome interaction; bare protein binding is uninformative and not elevated to core per guidelines. Supporting Evidence: file:human/SRP68/SRP68-uniprot.txt Q9UHB9; O76094: SRP72
GO:0005515 protein binding	IPI PMID:35156780 CFTR interactome mapping using the mammalian membrane two-hy...	KEEP AS NON CORE	Summary: CFTR-interactome mammalian membrane two-hybrid screen captured SRP68; the CFTR interaction is consistent with SRP engaging nascent membrane proteins but bare protein binding is uninformative. Reason: Screen-derived interaction; bare protein binding is uninformative and the CFTR partner reflects SRP substrate capture rather than a distinct core function. Supporting Evidence: file:human/SRP68/SRP68-uniprot.txt Q9UHB9; P13569: CFTR
GO:0005515 protein binding	IPI PMID:35271311 OpenCell: Endogenous tagging for the cartography of human ce...	KEEP AS NON CORE	Summary: OpenCell endogenous-tagging interactome capture; bare protein binding is uninformative. Reason: High-throughput interactome interaction; uninformative bare term not elevated to core. Supporting Evidence: file:human/SRP68/SRP68-uniprot.txt Q9UHB9; O76094: SRP72
GO:0005515 protein binding	IPI PMID:36012204 Differential CFTR-Interactome Proximity Labeling Procedures ...	KEEP AS NON CORE	Summary: CFTR-interactome proximity-labeling capture; bare protein binding is uninformative. Reason: Screen-derived interaction; uninformative bare term not elevated to core. Supporting Evidence: file:human/SRP68/SRP68-uniprot.txt Q9UHB9; P13569: CFTR
GO:0005786 signal recognition particle, endoplasmic reticulum targeting	NAS PMID:34208095 SRPassing Co-translational Targeting: The Role of the Signal...	ACCEPT	Summary: Review-based assertion that SRP68 is part of the ER-targeting SRP. Reason: Consistent with the experimentally supported SRP membership; the cited review summarizes mammalian SRP composition and function. Supporting Evidence: PMID:34208095 It is more complex in eukaryotes and consists of six proteins and one noncoding RNA in mammals.
GO:0006617 SRP-dependent cotranslational protein targeting to membrane, signal sequence recognition	NAS PMID:34208095 SRPassing Co-translational Targeting: The Role of the Signal...	ACCEPT	Summary: SRP, of which SRP68 is a core subunit, recognizes the signal sequence of nascent chains during cotranslational targeting; SRP68 participates in this signal-sequence-recognition step as part of the particle. Reason: Consistent with SRP's signal-sequence recognition role; SRP68 is an integral S-domain subunit of the recognizing particle. Supporting Evidence: PMID:34208095 SRP co-translationally targets proteins to the endoplasmic reticulum and prevents misfolding and aggregation of the secretory proteins in the cytoplasm
GO:0005829 cytosol	IDA GO_REF:0000052	ACCEPT	Summary: Direct immunofluorescence (HPA) evidence for cytosolic localization, consistent with the cytoplasmic SRP targeting cycle. Reason: IDA-supported cytosolic localization agrees with the documented cytoplasmic site of action. Supporting Evidence: file:human/SRP68/SRP68-uniprot.txt SUBCELLULAR LOCATION: Cytoplasm
GO:0005737 cytoplasm	EXP PMID:10618370 Signal recognition particle components in the nucleolus.	ACCEPT	Summary: Experimental (GFP-fusion) evidence that SRP68 localizes to the cytoplasm. Reason: Correct compartment; SRP acts in the cytoplasm. Supporting Evidence: PMID:10618370 green fluorescent protein fusions of SRP19, SRP68, and SRP72 localized to the nucleolus, as well as to the cytoplasm
GO:0005783 endoplasmic reticulum	EXP PMID:28369529 Human apo-SRP72 and SRP68/72 complex structures reveal the m...	ACCEPT	Summary: Experimental evidence for SRP68 ER localization, consistent with SRP docking at the ER-bound receptor. Reason: Correct; ER association reflects the targeting endpoint. The F590L mutant (disrupting SRP72 interaction) diminishes ER localization, linking ER targeting to heterodimer formation. Supporting Evidence: file:human/SRP68/SRP68-uniprot.txt F->L: Loss of interaction with SRP72. Diminished
GO:0008312 7S RNA binding	IMP PMID:27899666 Structures of human SRP72 complexes provide insights into SR...	ACCEPT	Summary: SRP68 binds and remodels the SRP (7S/7SL) RNA; structures of SRP68/72-RNA complexes establish the direct RNA-binding/remodeling activity. Reason: Core molecular function with direct structural support; SRP68-RBD binds the SRP RNA three-way junction and remodels the 5f loop. Supporting Evidence: PMID:27899666 the SRP72-RBD bound to the SRP S domain (SRP RNA, SRP19 and SRP68)
GO:0019904 protein domain specific binding	IPI PMID:27899666 Structures of human SRP72 complexes provide insights into SR...	KEEP AS NON CORE	Summary: SRP68 binds the SRP72 protein-binding domain (a TPR module) via an extended linear motif in its C-terminus; this domain-specific interaction mediates heterodimer formation. Reason: Captures the structurally defined SRP68-SRP72 PBD interaction; a genuine and informative interaction, but subsidiary to the core RNA-binding and SRP-targeting functions. Supporting Evidence: PMID:27899666 The SRP72-PBD is a tetratricopeptide repeat, which binds an extended linear motif of SRP68 with high affinity.
GO:0043022 ribosome binding	IMP PMID:27899666 Structures of human SRP72 complexes provide insights into SR...	ACCEPT	Summary: SRP68/72 contribute to SRP-ribosome contacts; SRP72-RBD remodels the 5f loop involved in ribosome binding, and the SRP68/72 module makes multiple ribosome contacts. Reason: Supported; the SRP68/72 heterodimer contributes to the particle's interaction with the translating ribosome during targeting. Supporting Evidence: PMID:27899666 SRP72-RBD remodels the 5f-loop involved in ribosome binding PMID:30649417
GO:0048500 signal recognition particle	IDA PMID:27899666 Structures of human SRP72 complexes provide insights into SR...	ACCEPT	Summary: SRP68 is a structurally demonstrated component of the signal recognition particle S domain. Reason: Core cellular component; directly demonstrated by structures of SRP68 within the SRP S domain. Supporting Evidence: PMID:27899666 the SRP72-RBD bound to the SRP S domain (SRP RNA, SRP19 and SRP68)
GO:0005515 protein binding	IPI PMID:24965446 Host factors that interact with the pestivirus N-terminal pr...	KEEP AS NON CORE	Summary: SRP68 was identified as a component of a pestivirus Npro-associated ribonucleoprotein complex; bare protein binding is uninformative for core SRP function. Reason: Captures a virus-host interactome observation; bare protein binding is uninformative and peripheral to core SRP function. Supporting Evidence: file:human/SRP68/SRP68-uniprot.txt Q9UHB9; O76094: SRP72
GO:0003723 RNA binding	HDA PMID:22658674 Insights into RNA biology from an atlas of mammalian mRNA-bi...	ACCEPT	Summary: SRP68 was captured in a high-throughput mRNA-interactome (RNA-binding proteome) study; consistent with its 7SL-RNA-binding function. Reason: Correct general molecular function; SRP68 is an RNA-binding protein (the more specific 7S RNA binding captures its physiological target). Supporting Evidence: file:human/SRP68/SRP68-uniprot.txt The N-terminus is required for RNA-binding.
GO:0005829 cytosol	TAS Reactome:R-HSA-1799332	ACCEPT	Summary: Reactome curation of SRP68 cytosolic localization within the SRP targeting reaction. Reason: Correct compartment; redundant with experimental cytosol/cytoplasm annotations. Supporting Evidence: file:human/SRP68/SRP68-uniprot.txt SUBCELLULAR LOCATION: Cytoplasm
GO:0005047 signal recognition particle binding	IPI PMID:17254600 Protein-induced conformational changes of RNA during the ass...	ACCEPT	Summary: SRP68 interacts with the SRP RNA/particle during assembly, driving protein-induced conformational changes of the SRP RNA. Reason: Core molecular function; SRP68 binding within the particle is supported by assembly/conformational-change studies. Supporting Evidence: file:human/SRP68/SRP68-uniprot.txt Binds the signal recognition particle RNA (7SL RNA), SRP72 binds to this complex subsequently
GO:0005786 signal recognition particle, endoplasmic reticulum targeting	IDA PMID:18089836 A new mechanism of 6-((2-(dimethylamino)ethyl)amino)-3-hydro...	ACCEPT	Summary: SRP68 was identified as part of the SRP via affinity capture; consistent with its established SRP membership. Reason: Correct core cellular component; redundant with stronger structural evidence. Supporting Evidence: file:human/SRP68/SRP68-uniprot.txt Component of a signal recognition particle (SRP) complex
GO:0009410 response to xenobiotic stimulus	IDA PMID:18089836 A new mechanism of 6-((2-(dimethylamino)ethyl)amino)-3-hydro...	KEEP AS NON CORE	Summary: SRP68/SRP72 were pulled out as binding targets of the anticancer drug TAS-103 using drug-immobilized affinity beads; this is an affinity-capture observation, peripheral to SRP68's core SRP function. Reason: Drug target-screening (affinity capture) observation; does not represent a core biological process of SRP68. Supporting Evidence: file:human/SRP68/SRP68-uniprot.txt Component of a signal recognition particle (SRP) complex
GO:0005730 nucleolus	TAS PMID:10618370 Signal recognition particle components in the nucleolus.	KEEP AS NON CORE	Summary: SRP68 localizes to the nucleolus (in addition to cytoplasm and ER), consistent with partial SRP assembly there; not the core site of action. Reason: Genuine localization reflecting SRP assembly trafficking, not the core cytosolic/ER targeting function. Supporting Evidence: PMID:10618370 green fluorescent protein fusions of SRP19, SRP68, and SRP72 localized to the nucleolus, as well as to the cytoplasm PMID:38858088
GO:0005783 endoplasmic reticulum	TAS PMID:10618370 Signal recognition particle components in the nucleolus.	ACCEPT	Summary: SRP68 accumulates at the ER, consistent with its affinity for the ER-bound SRP receptor. Reason: Correct; ER association reflects the targeting endpoint where SRP docks the nascent-chain complex. Supporting Evidence: PMID:10618370 SRP68 also accumulated in the ER, consistent with its affinity for the ER-bound SRP receptor.
GO:0005786 signal recognition particle, endoplasmic reticulum targeting	TAS PMID:10618370 Signal recognition particle components in the nucleolus.	ACCEPT	Summary: SRP68 is a component of the S domain of the ER-targeting SRP. Reason: Correct core cellular component. Supporting Evidence: PMID:10618370 The S domain contains unique sequence SRP RNA and four SRP proteins: SRP19, SRP54, SRP68, and SRP72.
GO:0005840 ribosome	TAS PMID:10618370 Signal recognition particle components in the nucleolus.	KEEP AS NON CORE	Summary: SRP, via the SRP68/72 module, contacts the translating ribosome; the ribosome localization reflects SRP engagement with ribosome-nascent chain complexes rather than SRP68 being a ribosomal protein. Reason: SRP68 is not a ribosomal subunit; it transiently associates with ribosomes during targeting. The functional ribosome-contact role is better captured by GO:0043022 ribosome binding. Supporting Evidence: PMID:10618370 SRP interacts with ribosomes to bring translating membrane and secreted proteins to the endoplasmic reticulum

Gene Description

Existing Annotations Review

Core Functions

RNA-binding scaffold subunit of the signal recognition particle that binds and remodels the SRP (7SL) RNA, opening the conserved 5f loop required for cotranslational targeting.

Component of the SRP S-domain that, in heterodimer with SRP72, mediates SRP-dependent cotranslational targeting of secretory and membrane proteins to the endoplasmic reticulum.

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