StAR-related lipid transfer domain protein 7 (STARD7) or gestational trophoblastic tumor gene-1 (GTT1) is a lipid transporter that specifically binds and transports phosphatidylcholine between membranes.[1]
Function and tissue distribution
StarD7 is found in the cytosol and associated with the mitochondrion.[1] When overproduced in the cell, mitochondrial levels of phosphatidylcholine rise.[1] High levels of the protein are found in tumor cells compared to normal cells, suggesting a role in cell proliferation.[2]
Structure
There are two forms of StarD7: StarD7-I and StarD7-II. The former is 295 amino acids long. StarD7-I possesses an additional 75 amino acids at its amino-terminus, which form a signaling sequence that targets it to the outer membrane of the mitochondrion.[1]
StarD7 contains a StAR-related transfer domain (START), from which it derives its name. Moreover, the protein is a member of the predominantly phosphatidylcholine transporter subfamily of START proteins, the StarD2 subfamily. It shares 25% sequence identity with StarD2.[1]
References