Figure 1.
Processing pathway of human proIAPP. The N-terminal and C-terminal flanking regions of proIAPP are colored red. Cleavage of proIAPP occurs at the two dibasic sites denoted with blue arrows. The C-terminal region of proIAPP is removed preferentially by PC(1/3), and the remaining dibasic residues are removed by CPE. Final processing of the C-terminus includes removal of the remaining Gly and amidation of the Tyr by PAM, leading to the processing intermediate proIAPP1–48. The N-terminal region is removed by PC2. There is an intramolecular disulfide bond in proIAPP1–48 and in mature IAPP.