SAR1B, SARA2, SARB, GTP-binding protein SAR1b, GTP-binding protein B, GTBPB
The protein encoded by this gene is a small GTPase that acts as a homodimer. The encoded protein is activated by the guanine nucleotide exchange factor PREB and is involved in protein transport from the endoplasmic reticulum to the Golgi. This protein is part of the COPII coat complex. Defects in this gene are a cause of chylomicron retention disease (CMRD), also known as Anderson disease (ANDD). Two transcript variants encoding the same protein have been found for this gene. [provided by RefSeq, Mar 2010],disease:Defects in SAR1B are the cause of chylomicron retention disease (CMRD) [MIM:246700], also known as Anderson disease (ANDD). CMRD is 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.,function:Involved in transport from the endoplasmic reticulum to the Golgi apparatus. Activated by the guanine nucleotide exchange factor PREB. Involved in the selection of the protein cargo and the assembly of the COPII coat complex.,similarity:Belongs to the small GTPase superfamily.,similarity:Belongs to the small GTPase superfamily. SAR1 family.,subcellular location:Associated with the endoplasmic reticulum and Golgi stacks, in particular in the juxta-nuclear Golgi region.,subunit:Homodimer. Binds PREB. Part of the COPII coat complex. Binds to the cytoplasmic tails of target proteins in the endoplasmic reticulum.,tissue specificity:Expressed in many tissues including small intestine, liver, muscle and brain.,
