DPP6 is a Type-II serine proteinase of the clan SC. The clan SC proteinases have a catalytic triad of Ser-Asp-His, and like other Serine proteinases, the active site serine is in a Gly-Xaa-Ser-Xaa -Gly orientation. DPP6 has an Asp instead of Ser in the catalytic site. DPP6 is a member of a broader family of dipeptidyl peptidases including DPP4, FAP/Seprase, DPP2, DPP8, DPP9, DPP10, which have differing substrate specificity and tissue localizations. The surface-bound DPP6 is a homodimer, and cleavage of in the stalk region releases a shed form of DPP6. The shed is the form found in serum. DPP6 has been found in highest abundance in the brain, but also in the kidney, liver and lung.