STARD5

StAR-related lipid transfer protein 5 is a protein that in humans is encoded by the STARD5 gene.^[5][6] The protein is a 213 amino acids long, consisting almost entirely of a StAR-related transfer (START) domain. It is also part of the StarD4 subfamily of START domain proteins, sharing 34% sequence identity with STARD4.

STARD5
Available structures PDB Ortholog search: PDBe RCSB List of PDB id codes 2R55
Identifiers
Aliases	STARD5, StAR related lipid transfer domain containing 5
External IDs	OMIM: 607050; MGI: 2156765; HomoloGene: 11346; GeneCards: STARD5; OMA:STARD5 - orthologs
Gene location (Human) Chr. Chromosome 15 (human)[1] Band 15q25.1 Start 81,309,053 bp[1] End 81,324,183 bp[1]
Gene location (Mouse) Chr. Chromosome 7 (mouse)[2] Band 7 D3|7 47.43 cM Start 83,281,167 bp[2] End 83,302,335 bp[2]
RNA expression pattern Bgee Human Mouse (ortholog) Top expressed in right lobe of liver skin of abdomen skin of leg ectocervix mucosa of transverse colon rectum vagina canal of the cervix body of uterus skin of thigh Top expressed in lip lacrimal gland right kidney proximal tubule epithelium of small intestine human kidney liver granulocyte skin of external ear left lobe of liver More reference expression data BioGPS More reference expression data
Gene ontology Molecular function bile acid binding lipid binding cholesterol binding cholesterol transfer activity Cellular component cytosol mitochondrion Biological process lipid transport cholesterol import bile acid and bile salt transport Sources:Amigo / QuickGO
Orthologs Species Human Mouse Entrez 80765 170460 Ensembl ENSG00000172345 ENSMUSG00000046027 UniProt Q9NSY2 Q9EPQ7 RefSeq (mRNA) NM_030574 NM_181900 NM_023377 RefSeq (protein) NP_871629 NP_075866 Location (UCSC) Chr 15: 81.31 – 81.32 Mb Chr 7: 83.28 – 83.3 Mb PubMed search [3] [4]
Wikidata
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Function

The protein is most prevalent in the kidney and the liver where it is found in Kupffer cells.^[5][7] STARD5 binds both cholesterol and 25-hydroxycholesterol and appears to function to redistribute cholesterol to the endoplasmic reticulum with which the protein associates and/or the plasma membrane.^[5][8][9] Increased levels of StarD5 increase free cholesterol in the cell.^[8]

Cholesterol homeostasis is regulated, at least in part, by sterol regulatory element (SRE)-binding proteins (e.g., SREBP1) and by liver X receptors (e.g., LXRA). Upon sterol depletion, LXRs are inactive and SREBPs are cleaved, after which they bind promoter SREs and activate genes involved in cholesterol biosynthesis and uptake. Sterol transport is mediated by vesicles or by soluble protein carriers, such as steroidogenic acute regulatory protein (STAR). STAR is homologous to a family of proteins containing a 200- to 210-amino acid STAR-related lipid transfer (START) domain, including STARD5.^[5][6]