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FLASH GENE
Symbol SAR1B contributors: mct/npt - updated : 31-01-2018
HGNC name SAR1 gene homolog B (S. cerevisiae)
HGNC id 10535
Corresponding disease
CMRD chylomicron retention disease
Location 5q31.1      Physical location : 133.936.840 - 133.968.533
Synonym name
  • SAR1a gene homolog 2 (S. cerevisiae)
  • GTP-binding protein Sara
  • Synonym symbol(s) SARA2, GTBPB, 2310075M17Rik, CMRD, SARB
    DNA
    TYPE functioning gene
    STRUCTURE 26.41 kb     7 Exon(s)
    MAPPING cloned Y linked N status provisional
    RNA
    TRANSCRIPTS type messenger
    text variants 1 and 2 encode the same protein
    identificationnb exonstypebpproduct
    ProteinkDaAAspecific expressionYearPubmed
    8 - 6651 22.3 198 - 2015 25826777
    7 - 6532 22.3 198 - 2015 25826777
    EXPRESSION
    Type
       expressed in (based on citations)
    organ(s)
    SystemOrgan level 1Organ level 2Organ level 3Organ level 4LevelPubmedSpeciesStageRna symbol
    Cardiovascularheart   highly Mus musculus
    Digestiveliver   highly Mus musculus
    Nervousbrain   moderately Mus musculus
    Respiratorylung   moderately Mus musculus
    tissue
    SystemTissueTissue level 1Tissue level 2LevelPubmedSpeciesStageRna symbol
    Connectiveadipose    Mus musculus
    Muscularstriatumskeletal predominantly Mus musculus
    cell lineage
    cell lines
    fluid/secretion
    at STAGE
    physiological period pregnancy
    Text placenta
    PROTEIN
    PHYSICAL PROPERTIES
    STRUCTURE
    motifs/domains
  • N-terminal amphipathic alpha helix
  • mono polymer homomer , dimer
    HOMOLOGY
    intraspecies paralog to SAR1A
    Homologene
    FAMILY
  • small GTPase superfamily
  • SAR1 family
  • CATEGORY transport carrier
    SUBCELLULAR LOCALIZATION     intracellular
    intracellular,cytoplasm,organelle,membrane
    intracellular,cytoplasm,organelle,endoplasmic reticulum
    intracellular,cytoplasm,organelle,Golgi
    intracellular,cytoplasm,cytosolic
    text peripheral membrane protein associated with the endoplasmic reticulum and golgi stacks, in particular in the juxta-nuclear golgi region
    basic FUNCTION
  • involved in the intracellular trafficking of proteins in COP-coated vesicles
  • involved in the vesicular COPII dependent transport of proteins from the endoplasmic reticulum (ER) to the Golgi apparatus (Silvain 2008)
  • playing an important role in processes involving erythroid cell proliferation and differentiation
  • plays a significant role in the assembly, organization, and function of the coat protein complex II, a critical complex for the transport of proteins from the endoplasmic reticulum to the Golgi
  • SAR1A and SAR1B proteins lower membrane rigidity at low concentrations, and at high concentrations, increase membrane rigidity
  • SAR1A, SAR1B GTPase coordinates the assembly of coat protein complex-II (COPII) at specific sites of the endoplasmic reticulum (ER)
  • SAR1A antagonizes the lipoprotein secretion-promoting activity of SAR1B, both isoforms modulate the expression of genes encoding cholesterol biosynthetic enzymes and the synthesis of cholesterol
  • SAR1B promotes the secretion of hepatic lipids but also adds regulation of cholesterol synthesis to SAR1B's repertoire of transport functions
  • importance of SAR1B in organs involved in lipid transport and/or calcium trafficking such as the liver, intestine, skeletal muscle and heart
  • SAR1A, SAR1B dimerization is responsible for the formation of constrictive membrane curvature
  • SAR1B GTPase is a key component of Coat protein complex II (COPII)-coated vesicles that bud from the endoplasmic reticulum to export newly synthesized proteins
  • SAR1B overexpression contributes to regulation of Cholestérol (CHOL) transport and metabolism by facilitating rapid uptake and transport of CHOL
  • Sar1B GTPase is one of the critical proteins governing chylomicron secretion by the small intestine
  • CELLULAR PROCESS
    PHYSIOLOGICAL PROCESS
    PATHWAY
    metabolism
    signaling
    a component
    INTERACTION
    DNA
    RNA
    small molecule nucleotide,
  • Mg2+
  • GTP
  • protein
  • may promote intestinal lipid transport with the involvement of the coat protein complex II network and the processing of SREBF1
  • promotes hepatic apolipoprotein (apo) B lipoprotein secretion and this promoting activity is coordinated with the processes regulating APOB expression and the transfer of triglycerides/cholesterol moieties onto this large lipid transport protein
  • cell & other
    REGULATION
    Other is regulated in a time- and concentration-dependent manner by dietary lipids, suggesting an adaptation to alimentary lipid flux
    ASSOCIATED DISORDERS
    corresponding disease(s) CMRD
    Susceptibility
    Variant & Polymorphism
    Candidate gene
    Marker
    Therapy target
    ANIMAL & CELL MODELS
  • Sar1b transgenic mice displayed higher gene expression in the liver, ileum, jejunum, proximal and distal colon compared to wild-type mice