Figure 1.

MMP domain structure and protein fold. a The various domain organizations of human MMPs are illustrated; S, signal peptide; Pro, propeptide; CAT, catalytic domain; F, fibronectin repeats; PEX, hemopexin domain; TM, transmembrane domain; GPI, glycophosphatidylinositol membrane anchor; C, cytoplasmic domain; CA, cysteine array; Ig, immunoglobulin-like domain. The flexible, variable length linker or hinge region is depicted as a wavy black ribbon. b The protein structure of the domains of a representative proMMP (proMMP-2) is shown; the individual domains, colored as in the cartoon above, have been separated for visual clarity. Dotted lines indicate the coordination of prodomain cysteine to the catalytic zinc (gray sphere), as well as the points of covalent attachment between the catalytic domain and the prodomain, fibronectin repeats, and PEX domain. Figure was generated with Pymol [155], using coordinates from Protein Databank entry 1GXD [156].