Transmembrane proteases in focus: diversity and redundancy?

Recent advances have led to the identification and characterization of an array of transmembrane proteases that mediate the proteolysis of various substrates (including bioactive peptides, components of the extracellular matrix, and integral proteins) and cell-cell or cell-matrix adhesion. The membrane proteases known to participate in these processes currently include the ectopeptidases, the membrane-type matrix metalloproteases (MT-MMPs), the ADAM (a disintegrin and metalloprotease) family, the meprins, and the secretases, and this list may be expected to grow. The roles that these molecules play within neoplastic and inflammatory sites are being investigated actively. The capacity of these ectoenzymes to transmit intracellular-transduction signals through the plasma membrane has to be considered. An appreciation of their functional redundancy is emerging.