MMP-23
MMP-23 (CA-MMP) is the most structurally divergent member of the matrix metalloproteinase family. Instead of the classic pro-domain it carries an N-terminal cysteine array with a signal anchor, and in place of the hemopexin domain its C-terminus bears a cysteine-rich immunoglobulin-like segment, features that set it clearly apart from all other matrixins. Expression is concentrated in reproductive organs, including ovary, prostate and testis, and in articular chondrocytes, with reports in osteoarthritic cartilage. Functional characterization is still limited; studies have implicated MMP-23 in cell-cycle control and in inflammatory regulation, and its unusual architecture suggests it acts more as a signaling-oriented sheddase than a classical matrix-degrading enzyme.
