ID:SAR1B_HUMAN DESCRIPTION: RecName: Full=GTP-binding protein SAR1b; AltName: Full=GTP-binding protein B; Short=GTBPB; 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. SUBUNIT: Homodimer. Binds PREB. Part of the COPII coat complex. Binds to the cytoplasmic tails of target proteins in the endoplasmic reticulum (By similarity). SUBCELLULAR LOCATION: Endoplasmic reticulum membrane; Peripheral membrane protein (By similarity). Golgi apparatus, Golgi stack membrane; Peripheral membrane protein (By similarity). Note=Associated with the endoplasmic reticulum and Golgi stacks, in particular in the juxta-nuclear Golgi region (By similarity). TISSUE SPECIFICITY: Expressed in many tissues including small intestine, liver, muscle and brain. 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. SIMILARITY: Belongs to the small GTPase superfamily. SAR1 family.
The RNAfold program from the Vienna RNA Package is used to perform the secondary structure predictions and folding calculations. The estimated folding energy is in kcal/mol. The more negative the energy, the more secondary structure the RNA is likely to have.
ModBase Predicted Comparative 3D Structure on Q9Y6B6
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Orthologous Genes in Other Species
Orthologies between human, mouse, and rat are computed by taking the best BLASTP hit, and filtering out non-syntenic hits. For more distant species reciprocal-best BLASTP hits are used. Note that the absence of an ortholog in the table below may reflect incomplete annotations in the other species rather than a true absence of the orthologous gene.
Biological Process: GO:0002474 antigen processing and presentation of peptide antigen via MHC class I GO:0006886 intracellular protein transport GO:0006888 ER to Golgi vesicle-mediated transport GO:0015031 protein transport GO:0016192 vesicle-mediated transport GO:0019886 antigen processing and presentation of exogenous peptide antigen via MHC class II GO:0048208 COPII vesicle coating
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Sequence and Links to Tools and Databases 
Common Gene Haplotype Alleles 
