The C-terminal domain of 72 kDa gelatinase A is not required for catalysis, but is essential for membrane activation and modulates interactions with tissue inhibitors of metalloproteinases

Recombinant 72 kDa gelatinase A and a truncated form lacking the C-terminal domain were shown to be activated by organomercurials and to possess similar activities towards a number of substrates. The truncated proenzyme differed from the full-length gelatinase in that it could not be activated by a membrane activator and did not bind tissue inhibitor of metalloproteinase (TIMP)-2. Kinetic studies also showed that the inhibition of the activated truncated enzyme, by both TIMP-1 and TIMP-2, was considerably decreased compared with the full-length enzyme. We conclude that the C-terminal domain plays an important role in the regulation of gelatinase A by a potential physiological activator and inhibitors.