Corin protein domain structure. Human corin consists of an N-terminal cytoplasmic tail, a transmembrane domain (TM), and an extracellular region that contains two frizzled (Fz) domains, eight LDL receptor (LDLR) repeats, a scavenger receptor (SR) domain, and a C-terminal serine protease domain. The catalytic residues His (H), Asp (D), and Ser (S) are shown. The activation cleavage site is located between the scavenger receptor domain and the protease domain. The predicted N-glycosylation sites are indicated by Y shaped symbols.