O04267 · SAR1B_BRACM
- ProteinSmall COPII coat GTPase SAR1B
- GeneSAR1B
- StatusUniProtKB reviewed (Swiss-Prot)
- Amino acids195 (go to sequence)
- Protein existenceEvidence at transcript level
- Annotation score3/5
Function
function
Small GTPase that cycles between an active GTP-bound and an inactive GDP-bound state and mainly functions in vesicle-mediated endoplasmic reticulum (ER) to Golgi transport. The active GTP-bound form inserts into the endoplasmic reticulum membrane where it recruits the remainder of the coat protein complex II/COPII. The coat protein complex II assembling and polymerizing on endoplasmic reticulum membrane is responsible for both the sorting of cargos and the deformation and budding of membranes into vesicles destined to the Golgi.
Catalytic activity
- GTP + H2O = GDP + H+ + phosphateThis reaction proceeds in the forward direction.
Activity regulation
Small GTPases activation is mediated by guanine exchange factors (GEF), while inactivation through hydrolysis of the bound GTP is stimulated by GTPase activating proteins (GAP).
Features
Showing features for binding site.
Type | ID | Position(s) | Description | |||
---|---|---|---|---|---|---|
Binding site | 29 | Mg2+ (UniProtKB | ChEBI) | ||||
Sequence: D | ||||||
Binding site | 30 | GDP (UniProtKB | ChEBI) | ||||
Sequence: N | ||||||
Binding site | 30 | GTP (UniProtKB | ChEBI) | ||||
Sequence: N | ||||||
Binding site | 31 | GDP (UniProtKB | ChEBI) | ||||
Sequence: A | ||||||
Binding site | 32 | GDP (UniProtKB | ChEBI) | ||||
Sequence: G | ||||||
Binding site | 32 | GTP (UniProtKB | ChEBI) | ||||
Sequence: G | ||||||
Binding site | 33 | GDP (UniProtKB | ChEBI) | ||||
Sequence: K | ||||||
Binding site | 33 | GTP (UniProtKB | ChEBI) | ||||
Sequence: K | ||||||
Binding site | 34 | GDP (UniProtKB | ChEBI) | ||||
Sequence: T | ||||||
Binding site | 34 | GTP (UniProtKB | ChEBI) | ||||
Sequence: T | ||||||
Binding site | 35 | GDP (UniProtKB | ChEBI) | ||||
Sequence: T | ||||||
Binding site | 35 | GTP (UniProtKB | ChEBI) | ||||
Sequence: T | ||||||
Binding site | 53 | GDP (UniProtKB | ChEBI) | ||||
Sequence: H | ||||||
Binding site | 70 | Mg2+ (UniProtKB | ChEBI) | ||||
Sequence: D | ||||||
Binding site | 129 | GDP (UniProtKB | ChEBI) | ||||
Sequence: N | ||||||
Binding site | 129 | GTP (UniProtKB | ChEBI) | ||||
Sequence: N | ||||||
Binding site | 130 | GDP (UniProtKB | ChEBI) | ||||
Sequence: K | ||||||
Binding site | 130 | GTP (UniProtKB | ChEBI) | ||||
Sequence: K | ||||||
Binding site | 132 | GDP (UniProtKB | ChEBI) | ||||
Sequence: D | ||||||
Binding site | 132 | GTP (UniProtKB | ChEBI) | ||||
Sequence: D | ||||||
Binding site | 177 | GDP (UniProtKB | ChEBI) | ||||
Sequence: I | ||||||
Binding site | 177 | GTP (UniProtKB | ChEBI) | ||||
Sequence: I |
GO annotations
Aspect | Term | |
---|---|---|
Cellular Component | endoplasmic reticulum membrane | |
Cellular Component | Golgi cisterna membrane | |
Molecular Function | GTP binding | |
Molecular Function | GTPase activity | |
Molecular Function | metal ion binding | |
Biological Process | intracellular protein transport | |
Biological Process | vesicle-mediated transport |
Keywords
- Molecular function
- Biological process
- Ligand
Enzyme and pathway databases
Names & Taxonomy
Protein names
- Recommended nameSmall COPII coat GTPase SAR1B
- EC number
- Alternative names
Gene names
Organism names
- Taxonomic lineageEukaryota > Viridiplantae > Streptophyta > Embryophyta > Tracheophyta > Spermatophyta > Magnoliopsida > eudicotyledons > Gunneridae > Pentapetalae > rosids > malvids > Brassicales > Brassicaceae > Brassiceae > Brassica
Accessions
- Primary accessionO04267
Proteomes
Subcellular Location
UniProt Annotation
GO Annotation
Endoplasmic reticulum membrane ; Peripheral membrane protein
Golgi apparatus, Golgi stack membrane ; Peripheral membrane protein
Note: Active at endoplasmic reticulum exit sites (ERES) where it inserts into the membrane and recruits the remainder of the coat protein complex II/COPII.
Keywords
- Cellular component
PTM/Processing
Features
Showing features for chain.
Type | ID | Position(s) | Description | |||
---|---|---|---|---|---|---|
Chain | PRO_0000206268 | 1-195 | Small COPII coat GTPase SAR1B | |||
Sequence: MFLFDWFYGILASLGLWQKEAKILFLGLDNAGKTTLLHMLKDERLVQHQPTQHPTSEELSIGKIKFKAFDLGGHQIARRVWKDYYAKVDAVVYLVDAYDKERFSESKKELDALLSDDALATVPFLILGNKIDNPYAASEDELRYHLGLTNFTTGKGKVTTAGGDSGVRPLEVFMCSIVRKMGYGEGFKWLSQYIN |
Expression
Tissue specificity
Expressed in most tissues.
Interaction
Subunit
Homodimer; upon association with membrane. Part of the coat protein complex II/COPII, composed of SEC23/24 and SEC13/31 heterodimers, that it helps recruit and assemble on endoplasmic reticulum (ER) membranes at ER exit site.
Structure
Family & Domains
Features
Showing features for motif, region.
Type | ID | Position(s) | Description | |||
---|---|---|---|---|---|---|
Motif | 2-4 | STAR; SAR1-N-terminal activation recruitment. Required for the activation and subsequent recruitment to ER membrane | ||||
Sequence: FLF | ||||||
Region | 10-14 | Mediates recruitment to ER membranes | ||||
Sequence: ILASL |
Sequence similarities
Belongs to the small GTPase superfamily. SAR1 family.
Family and domain databases
Sequence
- Sequence statusComplete
- Length195
- Mass (Da)22,077
- Last updated1997-07-01 v1
- ChecksumA2FC46B348F29D7B
Keywords
- Technical term