STARD7

StAR-related lipid transfer domain protein 7 (STARD7) or is_associated_with::gestational trophoblastic tumor gene-1 (GTT1) is a is_associated_with::lipid transporter that specifically binds and transports is_associated_with::phosphatidylcholine between membranes.

Function and tissue distribution
StarD7 is found in the is_associated_with::cytosol and associated with the is_associated_with::mitochondrion. When overproduced in the cell, mitochondrial levels of phosphatidylcholine rise. High levels of the protein are found in is_associated_with::tumor cells compared to normal cells, suggesting a role in cell proliferation.

Structure
There are two forms of StarD7: StarD7-I and StarD7-II. The former is 295 is_associated_with::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.

StarD7 contains a is_associated_with::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.