The matrix metalloproteinases (MMPs) are zinc dependent endopeptidases which cleave extracellular matrix (ECM) constituents, as well as non-matrix proteins. (MMPs) are also known as matrixins, hydrolyze components of the extracellular matrix. The members of this family contain a signal peptide, a propeptide and a catalytic domain. The catalytic domain contains two zinc ions and at least one calcium ion coordinated to various residues. All MMPs, with the exception matrilysin, have a hemopexin/vitronectin-like domain that is connected to the catalytic domain by a hinge or linker region. The hemopexin-like domain influences tissue inhibitor of metalloproteinases (TIMP) binding , membrane activation, and some proteolytic activities These proteinases play a central role in many biological processes, such as embryogenesis, normal tissue remodeling, wound healing, and angiogenesis, and in diseases such as atheroma, arthritis, cancer, and tissue ulceration. Currently 23 MMP genes have been identified in humans, and most are multi domain proteins. This review describes the members of the matrixin family and discusses substrate specificity, domain structure, functions, regulation of matrixin activity by tissue inhibitors of metalloproteinases, and their pathophysiological implication.
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