StAR Related Lipid Transfer Domain Containing Protein 4 (STARD4)

Cholesterol homeostasis is regulated, at least in part, by sterol regulatory element (SRE)-binding proteins and by liver X receptors. 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 STARD4.The deduced 205-amino acid human protein is 87% identical to the mouse protein and more similar to STARD5 and STARD6 than to STAR, STARD2 (PCTP), or STARD3 . It consists entirely of a START domain.