Sar1b
entrez
66397
canonical
uniprot
Q9CQC9
canonical
ensembl
ENSMUSG00000020386
resolver
ensp
ENSMUSP00000020653
resolver
enst
ENSMUST00000020653
resolver
genesymbol
Sar1b
resolver
genesymbol_syn
Sara1b
resolver
genesymbol_syn
Sara2
resolver
uniprot
Q0VGU0
resolver
uniprot
Q3UBL6
resolver
uniprot_entry
Q0VGU0_MOUSE
resolver
uniprot_entry
SAR1B_MOUSE
resolver
uniprot_sec
Q3UBL6
resolver
activity_regulation
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) (By similarity). Activated by the guanine nucleotide exchange factor PREB/SEC12 that facilitates the loading of SAR1B with GTP (By similarity). GTP hydrolysis is stimulated by SEC23/24 (By similarity). {ECO:0000250|UniProtKB:Q9QVY3, ECO:0000250|UniProtKB:Q9Y6B6}.
uniprot
proteins
amino_acid_sequence
MSFIFDWIYSGFSSVLQFLGLYKKSGKLVFLGLDNAGKTTLLHMLKDDRLGQHVPTLHPTSEELTIAGMTFTTFDLGGHVQARRVWKNYLPAINGIVFLVDCADHERLLESKEELDSLMTDETIANVPILILGNKIDRPEAISEERLREMFGLYGQTTGKGSVSLKELNARPLEVFMCSVLKRQGYGEGFRWMAQYID
uniprot
proteins
ec_number
3.6.5.2
uniprot
proteins
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 (By similarity). In contrast to SAR1A, SAR1B specifically interacts with the cargo receptor SURF4 to mediate the transport of lipid-carrying lipoproteins including APOB and APOA1 from the endoplasmic reticulum to the Golgi and thereby, indirectly regulates lipid homeostasis (PubMed:33186557). In addition to its role in vesicle trafficking, can also function as a leucine sensor regulating TORC1 signaling and more indirectly cellular metabolism, growth and survival. In absence of leucine, interacts with the GATOR2 complex via MIOS and inhibits TORC1 signaling. The binding of leucine abrogates the interaction with GATOR2 and the inhibition of the TORC1 signaling. This function is completely independent of the GTPase activity of SAR1B (By similarity). {ECO:0000250|UniProtKB:Q9Y6B6, ECO:0000269|PubMed:33186557}.
uniprot
proteins
mass_dalton
22382
uniprot
proteins
protein_family
SAR1 family
uniprot
proteins
protein_family
Small GTPase superfamily
uniprot
proteins
pubmed
11422940
uniprot
proteins
pubmed
15489334
uniprot
proteins
pubmed
16141072
uniprot
proteins
pubmed
21183079
uniprot
proteins
pubmed
33186557
uniprot
proteins
pubmed
33964306
uniprot
proteins
sequence_length
198
uniprot
proteins
subcellular_location
SUBCELLULAR LOCATION: Endoplasmic reticulum membrane {ECO:0000269|PubMed:11422940}; Peripheral membrane protein {ECO:0000269|PubMed:11422940}. Golgi apparatus, Golgi stack membrane {ECO:0000269|PubMed:11422940}; Peripheral membrane protein {ECO:0000269|PubMed:11422940}. Cytoplasm, cytosol {ECO:0000250|UniProtKB:Q9Y6B6}. Lysosome membrane {ECO:0000250|UniProtKB:Q9Y6B6}. 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. Upon leucine deprivation, associates with lysosomal membranes to repress TORC1 signaling. {ECO:0000250|UniProtKB:Q9Y6B6}.
uniprot
proteins