SAR1B
entrez
51128
canonical
uniprot
Q9Y6B6
canonical
ensembl
ENSG00000152700
resolver
ensp
ENSP00000385432
resolver
ensp
ENSP00000404997
resolver
ensp
ENSP00000423197
resolver
ensp
ENSP00000424673
resolver
ensp
ENSP00000425339
resolver
ensp
ENSP00000426335
resolver
ensp
ENSP00000573548
resolver
ensp
ENSP00000573550
resolver
ensp
ENSP00000573551
resolver
ensp
ENSP00000573552
resolver
ensp
ENSP00000573553
resolver
ensp
ENSP00000573554
resolver
ensp
ENSP00000573555
resolver
ensp
ENSP00000573557
resolver
ensp
ENSP00000573558
resolver
ensp
ENSP00000573559
resolver
ensp
ENSP00000620623
resolver
ensp
ENSP00000620624
resolver
ensp
ENSP00000620627
resolver
ensp
ENSP00000620628
resolver
enst
ENST00000402673
resolver
enst
ENST00000439578
resolver
enst
ENST00000502539
resolver
enst
ENST00000507419
resolver
enst
ENST00000509937
resolver
enst
ENST00000903489
resolver
enst
ENST00000903491
resolver
enst
ENST00000903492
resolver
enst
ENST00000903493
resolver
enst
ENST00000903494
resolver
enst
ENST00000903495
resolver
enst
ENST00000903496
resolver
enst
ENST00000903498
resolver
enst
ENST00000903499
resolver
enst
ENST00000903500
resolver
enst
ENST00000950564
resolver
enst
ENST00000950565
resolver
enst
ENST00000950568
resolver
enst
ENST00000950569
resolver
genesymbol
DKFZp434B2017
resolver
genesymbol
SAR1B
resolver
genesymbol_syn
SARA2
resolver
genesymbol_syn
SARB
resolver
hgnc
HGNC:10535
resolver
uniprot
D3DQA4
resolver
uniprot
F6RUA4
resolver
uniprot
Q567T4
resolver
uniprot
Q9H029
resolver
uniprot_entry
F6RUA4_HUMAN
resolver
uniprot_entry
Q9H029_HUMAN
resolver
uniprot_entry
SAR1B_HUMAN
resolver
uniprot_sec
D3DQA4
resolver
uniprot_sec
Q567T4
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 (PubMed:32358066). GTP hydrolysis is stimulated by SEC23/24 (By similarity). {ECO:0000250|UniProtKB:Q9QVY3, ECO:0000269|PubMed:32358066}.
uniprot
proteins
amino_acid_sequence
MSFIFDWIYSGFSSVLQFLGLYKKTGKLVFLGLDNAGKTTLLHMLKDDRLGQHVPTLHPTSEELTIAGMTFTTFDLGGHVQARRVWKNYLPAINGIVFLVDCADHERLLESKEELDSLMTDETIANVPILILGNKIDRPEAISEERLREMFGLYGQTTGKGSISLKELNARPLEVFMCSVLKRQGYGEGFRWMAQYID
uniprot
proteins
disease_involvement
DISEASE: Chylomicron retention disease (CMRD) [MIM:246700]: An autosomal recessive disorder of severe fat malabsorption associated with failure to thrive in infancy. The condition is characterized by deficiency of fat-soluble vitamins, low blood cholesterol levels, and a selective absence of chylomicrons from blood. Affected individuals accumulate chylomicron-like particles in membrane-bound compartments of enterocytes, which contain large cytosolic lipid droplets. {ECO:0000269|PubMed:12692552, ECO:0000269|PubMed:17309654, ECO:0000269|PubMed:19274794}. Note=The disease is caused by variants affecting the gene represented in this entry.
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 (PubMed:23433038, PubMed:32358066, PubMed:33186557, PubMed:36369712). 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 (PubMed:23433038, PubMed:32358066, PubMed:33186557). 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:32358066, 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 (PubMed:34290409). {ECO:0000269|PubMed:23433038, ECO:0000269|PubMed:32358066, ECO:0000269|PubMed:33186557, ECO:0000269|PubMed:34290409, ECO:0000269|PubMed:36369712}.
uniprot
proteins
mass_dalton
22410
uniprot
proteins
mutagenesis
MUTAGEN 58; /note="H->A: Loss of interaction with MIOS. Loss of localization to lysosomal membrane. Loss of function in negative regulation of TORC1 signaling."; /evidence="ECO:0000269|PubMed:34290409"; MUTAGEN 79; /note="H->G: Loss of GTPase activity. Constitutively restricted in GTP active state."; /evidence="ECO:0000269|PubMed:36369712"; MUTAGEN 100; /note="V->A: Loss of leucine binding. Constitutive negative regulation of TORC1 signaling."; /evidence="ECO:0000269|PubMed:34290409"; MUTAGEN 114; /note="E->A: Loss of interaction with MIOS. Loss of localization to lysosomal membrane. Loss of function in negative regulation of TORC1 signaling."; /evidence="ECO:0000269|PubMed:34290409"; MUTAGEN 122; /note="E->A: Loss of interaction with MIOS. Loss of localization to lysosomal membrane. Loss of function in negative regulation of TORC1 signaling."; /evidence="ECO:0000269|PubMed:34290409"; MUTAGEN 141; /note="A->D: Loss of leucine binding. Constitutive negative regulation of TORC1 signaling."; /evidence="ECO:0000269|PubMed:34290409"; MUTAGEN 144; /note="E->A: Loss of leucine binding. Constitutive negative regulation of TORC1 signaling."; /evidence="ECO:0000269|PubMed:34290409
uniprot
proteins
protein_family
SAR1 family
uniprot
proteins
protein_family
Small GTPase superfamily
uniprot
proteins
pubmed
12692552
uniprot
proteins
pubmed
15489334
uniprot
proteins
pubmed
17309654
uniprot
proteins
pubmed
19274794
uniprot
proteins
pubmed
21269460
uniprot
proteins
pubmed
23433038
uniprot
proteins
pubmed
24275569
uniprot
proteins
pubmed
32358066
uniprot
proteins
pubmed
33186557
uniprot
proteins
pubmed
34290409
uniprot
proteins
pubmed
36369712
uniprot
proteins
sequence_length
198
uniprot
proteins
subcellular_location
SUBCELLULAR LOCATION: Endoplasmic reticulum membrane {ECO:0000269|PubMed:33186557}; Peripheral membrane protein {ECO:0000250|UniProtKB:Q9QVY3}. Golgi apparatus, Golgi stack membrane {ECO:0000250|UniProtKB:Q9QVY3}; Peripheral membrane protein {ECO:0000250|UniProtKB:Q9QVY3}. Cytoplasm, cytosol {ECO:0000269|PubMed:34290409}. Lysosome membrane {ECO:0000269|PubMed:34290409}. 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 (PubMed:23433038). Upon leucine deprivation, associates with lysosomal membranes to repress TORC1 signaling (PubMed:34290409). {ECO:0000269|PubMed:23433038, ECO:0000269|PubMed:34290409}.
uniprot
proteins