Oxysterol Binding Protein (OSBP)

Oxysterol binding protein is an intracellular protein that is believed to transport sterols from lysosomes to the nucleus where the sterol down-regulates the genes for the LDL receptor, HMG-CoA reductase, and HMG synthetase.

Oxysterol-binding proteins are evolutionary related proteins involved with sterol synthesis and/or its regulation. These include mammalian oxysterol-binding protein (OSBP), a protein of about 800 amino-acid residues that binds a variety of oxysterols (oxygenated derivatives of cholesterol); yeast OSH1, a protein of 859 residues that also plays a role in ergosterol synthesis; and yeast proteins HES1 and KES1, highly related proteins of 434 residues that seem to play a role in ergosterol synthesis