SREBP Cleavage Activating Protein (SCAP)

SCAP) is a regulatory protein that is required for the proteolytic cleavage of the sterol regulatory element binding protein (SREBP). SCAP is an integral membrane protein located in the endoplasmic reticulum (ER). One of the cytosolic regions of SCAP contains a hexapeptide amino acid sequence, MELADL, that functions to detect cellular cholesterol. When cholesterol is present, SCAP undergoes a conformational change that prevents it from activating SREBP and cholesterol synthesis does not occur.

Scap has 8 transmembrane domains and both the N terminal and C terminal face the cytoplasm. Also, it binds SREBP by a series of consecutive WD repeats on its C-terminus.