SAR1A

SAR1A (mammalian name) or Sar1 (yeast name) is a protein involved in membrane trafficking. It is a monomeric small GTPase found in COPII vesicles. It regulates the assembly and disassembly of COPII coats.

SAR1A
Available structures PDB Ortholog search: PDBe RCSB List of PDB id codes 2GAO
Identifiers
Aliases	SAR1A, SAR1, SARA1, Sara, masra2, secretion associated Ras related GTPase 1A
External IDs	OMIM: 607691 MGI: 98230 HomoloGene: 90897 GeneCards: SAR1A
Gene location (Human) Chr. Chromosome 10 (human)[1] Band 10q22.1 Start 70,147,289 bp[1] End 70,170,523 bp[1]
Gene location (Mouse) Chr. Chromosome 10 (mouse)[2] Band 10|10 B4 Start 61,680,299 bp[2] End 61,693,297 bp[2]
Gene ontology Molecular function • nucleotide binding • GTP binding • GO:0001948 protein binding • GTPase activity Cellular component • Golgi apparatus • intracellular • endoplasmic reticulum • Golgi membrane • COPII vesicle coat • endoplasmic reticulum exit site Biological process • protein transport • intracellular protein transport • vesicle-mediated transport • cargo loading into COPII-coated vesicle • regulation of COPII vesicle coating • ER to Golgi vesicle-mediated transport • vesicle organization • membrane organization • positive regulation of protein exit from endoplasmic reticulum Sources:Amigo / QuickGO
Orthologs
Species	Human	Mouse
Entrez	56681	20224
Ensembl	ENSG00000079332	ENSMUSG00000020088
UniProt	Q9NR31	P36536 Q99JZ4
RefSeq (mRNA)	NM_020150 NM_001142648	NM_009120 NM_001358487 NM_001358488
RefSeq (protein)	NP_001136120 NP_064535	NP_033146
Location (UCSC)	Chr 10: 70.15 – 70.17 Mb	Chr 10: 61.68 – 61.69 Mb
PubMed search	[3]	[4]
Wikidata
View/Edit Human View/Edit Mouse

[GDP]-bound Sar1 interacts with the membrane-bound exchange factor Sec12 and exchanges its bound GDP for GTP. The hydrophobic N-terminus of Sar1-GTP then locates it to the membrane, where it serves as the binding site for the Sec23/Sec24 protein coat complex. After the vesicle coat is completely assembled and the vesicle is released from the donor membrane, the Sec23 subunit promotes Sar1 GTPase activity, which triggers the disassembly of the COPII coat.