The steroidogenic acute regulatory protein (StAR) mediates the rate-limiting step of
steroidogenesis, delivery of cholesterol to the inner mitochondrial membrane. However, the
mechanism whereby cholesterol translocation is accomplished has not been resolved.
Recombinant StAR proteins lacking the first N-terminal 62 amino acids comprising the
mitochondrial-targeting sequence were used to determine if StAR binds cholesterol and
alters mitochondrial membrane cholesterol domains to enhance sterol transfer. First, a …