The Journal of biological chemistry
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Mouse mast cell protease (mMCP) 1, mMCP-2, mMCP-4, and mMCP-5 are serine proteases which are predicted to have chymotryptic specificity (chymases). They are bound to negatively charged heparin or chondroitin sulfate proteoglycans and are stored in secretory granules. Three-dimensional (3D) models of these four proteases were constructed with a comparative molecular modeling technique based on satisfaction of spatial constraints. ⋯ Thus, they are good candidates for binding sites that interact with heparin proteoglycan in the granules of serosal mast cells. In contrast, mMCP-1 and mMCP-2, which are present in granules of mucosal mast cells that contain chondroitin sulfate, lack one of these regions and have a lower charge density in the other. The differences between the 3D models provide a structural basis for the selective localization of specific chymases within mouse mast cells that contain different proteoglycans.