Table 1.
Molecules | Functions | Soluble form in the blood |
---|---|---|
DPP-4 | Type II membrane glycoprotein with dipeptidyl peptidase activity | Yes |
| ||
FAP (Seprase) | (i) Type II membrane glycoprotein with dipeptidyl peptidase, collagenase, and gelatinase activity (ii) Involved in extracellular matrix degradation, tissue remodeling, and fibrosis [15] (iii) Can heterodimerize with DPP-4 for efficient tissue remodeling [16] |
Yes |
| ||
DPP-7 (QPP, DPP-II) | (i) Intracellular location with dipeptidyl peptidase activity (ii) Most of its physiological substrate is unknown (iii) Secreted in an active form in response to calcium [17] (iv) Regulation of apoptotic pathway in quiescent lymphocytes [17] |
Unknown |
| ||
DPP-8/DPP-9 | (i) Intracellular localization with dipeptidyl peptidase activity (ii) Seems to be involved in M1 macrophage activation [18] (iii) Up-regulation of DPP-9 during monocyte to macrophage differentiation [18] (iv) Can cleave releasable neuropeptide Y (NPY) in brain [19] (v) The regulation of cellular proliferation and apoptosis [19] |
No |
| ||
DPP-6 and DPP-10 | (i) Transmembrane proteins with no peptidase activity (ii) Binds to specific voltage-gated K+ channels, altering their structures and biophysical properties [20] |
No |