GRAMD1B Cholesterol transporter that mediates non-vesicular transport of cholesterol from the plasma membrane (PM) to the endoplasmic reticulum (ER). Contains unique domains for binding cholesterol and the PM, thereby serving as a molecular bridge for the transfer of cholesterol from the PM to the ER. Plays a crucial role in cholesterol homeostasis in the adrenal gland and has the unique ability to localize to the PM based on the level of membrane cholesterol. In lipid-poor conditions localizes to the ER membrane and in response to excess cholesterol in the PM is recruited to the endoplasmic reticulum-plasma membrane contact sites (EPCS) which is mediated by the GRAM domain. At the EPCS, the sterol-binding VASt/ASTER domain binds to the cholesterol in the PM and facilitates its transfer from the PM to ER. 4 alternatively spliced human isoforms have been reported. Note: This description may include information from UniProtKB.
Protein type: Membrane protein, integral
Chromosomal Location of human Ortholog: 11q24.1
Cellular Component:  endoplasmic reticulum membrane; endoplasmic reticulum-plasma membrane contact site; plasma membrane
Molecular Function:  cholesterol binding; cholesterol transfer activity; phosphatidic acid binding; phosphatidylserine binding
Biological Process:  cellular response to cholesterol; cholesterol homeostasis; intermembrane lipid transfer; intracellular sterol transport
Reference #:  Q3KR37 (UniProtKB)
Alt. Names/Synonyms: ASTRB; GRAM domain containing 1B; GRAM domain-containing protein 1B; GRAMD1B; GRM1B; KIAA1201; LINC01059; long intergenic non-protein coding RNA 1059; MGC125622; MGC125623; MGC125625; Protein Aster-B
Gene Symbols: GRAMD1B
Molecular weight: 85,400 Da
Basal Isoelectric point: 5.84  Predict pI for various phosphorylation states
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Protein Structure Not Found.

Cross-references to other databases:  AlphaFold  |  STRING  |  cBioPortal  |  Wikipedia  |  neXtProt  |  Protein Atlas  |  BioGPS  |  Pfam  |  Phospho.ELM  |  NetworKIN  |  UniProtKB  |  Entrez-Gene  |  GenPept  |  Ensembl Gene  |  Ensembl Protein