The C-terminal domain of tissue inhibitor of metalloproteinases-2 is required for cell binding but not for antimetalloproteinase activity

We have generated a C-terminally-truncated form of recombinant tissue inhibitor of metalloproteinases-2 (designated rTIMP-2 delta) in which the region of the inhibitor extending from residue 128 to 194 and including 3 of the 6 disulfide bonds is deleted. rTIMP-2 and rTIMP-2 delta had similar inhibitory activities toward interstitial collagenase and inhibited the activation of the precursor form of matrix metalloproteinase-2 (proMMP-2). rTIMP-2 also bound with high affinity (Kd 0.99 nM) to HT1080 human fibrosarcoma cells treated with 12-O-tetradecanoyl-phorbol-13-acetate. However deletion of the C-terminal domain of TIMP-2 significantly lowered the cell surface binding affinity, with competition experiments indicating a 2 order of magnitude difference between rTIMP-2 and rTIMP-2 delta in the concentrations needed to displace I-125-labeled rTIMP-2 binding. These data indicate that the C-terminal domain of TIMP-2 is not required for the antimetalloproteinase activity but plays a major role in the high affinity cell surface binding of the inhibitor. (C) 1997 Academic Press.