Small COPII coat GTPase SAR1B

Details

Name
Small COPII coat GTPase SAR1B
Kind
protein
Synonyms
  • 3.6.5.2
  • GTBPB
  • GTP-binding protein B
  • SARA2
  • SARB
  • Secretion-associated Ras-related GTPase 1B
Gene Name
SAR1B
UniProtKB Entry
Q9Y6B6Swiss-Prot
Organism
Humans
NCBI Taxonomy ID
9606
Amino acid sequence
>lcl|BSEQ0013230|Small COPII coat GTPase SAR1B
MSFIFDWIYSGFSSVLQFLGLYKKTGKLVFLGLDNAGKTTLLHMLKDDRLGQHVPTLHPT
SEELTIAGMTFTTFDLGGHVQARRVWKNYLPAINGIVFLVDCADHERLLESKEELDSLMT
DETIANVPILILGNKIDRPEAISEERLREMFGLYGQTTGKGSISLKELNARPLEVFMCSV
LKRQGYGEGFRWMAQYID
Number of residues
198
Molecular Weight
22409.695
Theoretical pI
Not Available
GO Classification
Functions
amino acid sensor activity / G protein activity
Processes
cellular response to leucine starvation / COPII-coated vesicle cargo loading / endoplasmic reticulum to Golgi vesicle-mediated transport / lipid export from cell / lipid homeostasis / lipoprotein transport / negative regulation of TORC1 signaling / positive regulation of protein exit from endoplasmic reticulum / regulation of COPII vesicle coating / regulation of lipid transport / regulation of TORC1 signaling / vesicle organization
Components
COPII vesicle coat / endoplasmic reticulum exit site / lysosomal membrane
General 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)
Specific Function
amino acid sensor activity
Pfam Domain Function
Signal Regions
Not Available
Transmembrane Regions
Not Available
Cellular Location
Endoplasmic reticulum membrane
Gene sequence
>lcl|BSEQ0013231|GTP-binding protein SAR1b (SAR1B)
ATGTCCTTCATATTTGATTGGATTTACAGTGGTTTCAGCAGTGTGCTACAGTTTTTAGGA
TTATATAAGAAAACTGGTAAACTGGTATTTCTTGGATTGGATAATGCAGGAAAAACAACA
TTGCTACACATGCTAAAAGATGACAGACTTGGACAACATGTCCCAACATTACATCCCACT
TCCGAAGAACTGACCATTGCTGGCATGACGTTTACAACTTTTGATCTGGGTGGACATGTT
CAAGCTCGAAGAGTGTGGAAAAACTACCTTCCTGCTATCAATGGCATTGTATTTCTGGTG
GATTGTGCAGACCACGAAAGGCTGTTAGAGTCAAAAGAAGAACTTGATTCACTAATGACA
GATGAAACCATTGCTAATGTGCCTATACTGATTCTTGGGAATAAGATCGACAGACCTGAA
GCCATCAGTGAAGAGAGGTTGCGAGAGATGTTTGGTTTATATGGTCAGACAACAGGAAAG
GGGAGTATATCTCTGAAAGAACTGAATGCCCGACCCTTAGAAGTTTTCATGTGTAGTGTG
CTCAAAAGACAAGGTTACGGAGAAGGCTTCCGCTGGATGGCACAGTACATTGATTAA
Chromosome Location
5
Locus
5q31.1
External Identifiers
ResourceLink
UniProtKB IDQ9Y6B6
UniProtKB Entry NameSAR1B_HUMAN
GeneCard IDSAR1B
HGNC IDHGNC:10535
PDB ID(s)8E0A, 8E0B, 8E0C, 8E0D
KEGG IDhsa:51128
NCBI Gene ID51128
General References
  1. Gerhard DS, Wagner L, Feingold EA, Shenmen CM, Grouse LH, Schuler G, Klein SL, Old S, Rasooly R, Good P, Guyer M, Peck AM, Derge JG, Lipman D, Collins FS, Jang W, Sherry S, Feolo M, Misquitta L, Lee E, Rotmistrovsky K, Greenhut SF, Schaefer CF, Buetow K, Bonner TI, Haussler D, Kent J, Kiekhaus M, Furey T, Brent M, Prange C, Schreiber K, Shapiro N, Bhat NK, Hopkins RF, Hsie F, Driscoll T, Soares MB, Casavant TL, Scheetz TE, Brown-stein MJ, Usdin TB, Toshiyuki S, Carninci P, Piao Y, Dudekula DB, Ko MS, Kawakami K, Suzuki Y, Sugano S, Gruber CE, Smith MR, Simmons B, Moore T, Waterman R, Johnson SL, Ruan Y, Wei CL, Mathavan S, Gunaratne PH, Wu J, Garcia AM, Hulyk SW, Fuh E, Yuan Y, Sneed A, Kowis C, Hodgson A, Muzny DM, McPherson J, Gibbs RA, Fahey J, Helton E, Ketteman M, Madan A, Rodrigues S, Sanchez A, Whiting M, Madari A, Young AC, Wetherby KD, Granite SJ, Kwong PN, Brinkley CP, Pearson RL, Bouffard GG, Blakesly RW, Green ED, Dickson MC, Rodriguez AC, Grimwood J, Schmutz J, Myers RM, Butterfield YS, Griffith M, Griffith OL, Krzywinski MI, Liao N, Morin R, Palmquist D, Petrescu AS, Skalska U, Smailus DE, Stott JM, Schnerch A, Schein JE, Jones SJ, Holt RA, Baross A, Marra MA, Clifton S, Makowski KA, Bosak S, Malek J: The status, quality, and expansion of the NIH full-length cDNA project: the Mammalian Gene Collection (MGC). Genome Res. 2004 Oct;14(10B):2121-7. [Article]
  2. Burkard TR, Planyavsky M, Kaupe I, Breitwieser FP, Burckstummer T, Bennett KL, Superti-Furga G, Colinge J: Initial characterization of the human central proteome. BMC Syst Biol. 2011 Jan 26;5:17. doi: 10.1186/1752-0509-5-17. [Article]
  3. Bian Y, Song C, Cheng K, Dong M, Wang F, Huang J, Sun D, Wang L, Ye M, Zou H: An enzyme assisted RP-RPLC approach for in-depth analysis of human liver phosphoproteome. J Proteomics. 2014 Jan 16;96:253-62. doi: 10.1016/j.jprot.2013.11.014. Epub 2013 Nov 22. [Article]
  4. Jones B, Jones EL, Bonney SA, Patel HN, Mensenkamp AR, Eichenbaum-Voline S, Rudling M, Myrdal U, Annesi G, Naik S, Meadows N, Quattrone A, Islam SA, Naoumova RP, Angelin B, Infante R, Levy E, Roy CC, Freemont PS, Scott J, Shoulders CC: Mutations in a Sar1 GTPase of COPII vesicles are associated with lipid absorption disorders. Nat Genet. 2003 May;34(1):29-31. [Article]
  5. Annesi G, Aguglia U, Tarantino P, Annesi F, De Marco EV, Civitelli D, Torroni A, Quattrone A: SIL1 and SARA2 mutations in Marinesco-Sjogren and chylomicron retention diseases. Clin Genet. 2007 Mar;71(3):288-9. [Article]
  6. Treepongkaruna S, Chongviriyaphan N, Suthutvoravut U, Charoenpipop D, Choubtum L, Wattanasirichaigoon D: Novel missense mutations of SAR1B gene in an infant with chylomicron retention disease. J Pediatr Gastroenterol Nutr. 2009 Mar;48(3):370-3. [Article]

Associated Data

Drug Relations
DrugDrug groupPharmacological action?TypeActionsDetails
Guanosine-5'-DiphosphateexperimentalunknowntargetDetails