StAR-related lipid transfer domain protein 7 (STARD7) or gestational trophoblastic tumor gene-1 (GTT1) is a

lipid Lipids are a broad group of naturally-occurring molecules which includes fats, waxes, sterols, fat-soluble vitamins (such as vitamins A, D, E and K), monoglycerides, diglycerides, phospholipids, and others. The functions of lipids includ ...

transporter that specifically binds and transports

phosphatidylcholine Phosphatidylcholines (PC) are a class of phospholipids that incorporate choline as a headgroup. They are a major component of biological membranes and can be easily obtained from a variety of readily available sources, such as egg yolk or soybea ...

between membranes.

Function and tissue distribution

StarD7 is found in the

cytosol The cytosol, also known as cytoplasmic matrix or groundplasm, is one of the liquids found inside cells ( intracellular fluid (ICF)). It is separated into compartments by membranes. For example, the mitochondrial matrix separates the mitochondri ...

and associated with the mitochondrion. When overproduced in the cell, mitochondrial levels of phosphatidylcholine rise. High levels of the protein are found in

tumor A neoplasm () is a type of abnormal and excessive growth of tissue. The process that occurs to form or produce a neoplasm is called neoplasia. The growth of a neoplasm is uncoordinated with that of the normal surrounding tissue, and persists ...

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 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 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.

References

{{Reflist Genes on human chromosome 2 Water-soluble transporters