Matrix metalloproteinases (MMPs) or matrixins may play a role in the degradation and remodeling of the extracellular matrix (ECM) during development or in response to stresses (By similarity). Required for plant growth, morphogenesis, and development with particular relevance for flowering and senescence (PubMed:11726650). Active on McaPLGLDpaAR-NH(2) (QF24) and myelin basic protein (MBP) and, to some extent, on beta-casein (PubMed:24156403). Binds 1 zinc ion per subunit. Repressed by acetohydroxamic acid (AHA). Optimum pH is 7-8. Optimum temperature is 45 degrees Celsius. Mostly expressed in roots, and, to a lower extent, in flowers, leaves and stems. Accumulates during aging. Expressed in leaves and roots of young seedlings and in leaves, roots, and inflorescences of mature flowering plants. In leaves, present in the phloem, in developing xylem elements, epidermal cells, and neighboring mesophyll cell layers. In flowers, localized in pistils, ovules, and receptacles. Induced in seedling rosette leaves by methyl jasmonate (MeJA) and cadmium (Cd). Induced in seedling roots by salt stress (NaCl). Inhibited in leaves and inflorescences of adult plants by exposure to cadmium. The conserved cysteine present in the cysteine-switch motif binds the catalytic zinc ion, thus inhibiting the enzyme. The dissociation of the cysteine from the zinc ion upon the activation-peptide release activates the enzyme. Growth inhibition, due to inhibited onset of shoots, reduced growth of roots, leaves and shoots, late flowering, fast degradation of chlorophyll in leaves and early senescence. Belongs to the peptidase M10A family. Matrix metalloproteinases (MMPs) subfamily.