Interaction of matrix metalloproteinases-2 and -9 with pregnancy zone protein and alpha(2)-macroglobulin

The binding of matrix metalloproteinases-2 and -9 to pregnancy zone protein and alpha(2)-macroglobulin was studied. The binding was demonstrated by formation of dimeric as well as tetrameric complexes of pregnancy zone protein and by the formation of alpha(2)-macroglobulin complexes with fast and intermediate mobility in native gel electrophoresis. The complex formation was confirmed by the use of I-125-labeled matrix metalloproteinase-2. The cleavage sites in the ''bait'' regions following formation of high-molecular-weight complexes of matrix metalloproteinases with the alpha-macroglobulins were determined by protein sequence analysis. Pregnancy zone protein was cleaved at Thr(693)-Tyr(694) and alpha(2)-macroglobulin at Gly(679)-Leu(680) and Arg(696)-Leu(697) by matrix metalloproteinase-2. Matrix metalloproteinase-9 cleaved alpha(2)-macroglobulin at the same site as matrix metalloproteinase-2, but cleavage of pregnancy zone protein was at Leu(753)-Ser(754). The sequences of the bands, visualized in the SDS gel, of approximately 90 and 165 kDa or higher molecular weight complexes were the same. This indicates that the matrix metalloproteinases cleaved the inhibitors with or without binding to them. The present results suggest that matrix metalloproteinases-2 and -9 may interact with pregnancy zone protein and alpha(2)-macroglobulin in vivo. (C) 1997 Academic Press.