Proteases

Presenilins are a family of related multi-pass transmembrane proteins that function as a part of the gamma-secretase protease complex. Presenilins undergo cleavage in an alpha helical region of one of the cytoplasmic loops to produce a larger N-terminal and a smaller C-terminal fragment which together form part of the functional protein. Cleavage of presenilin 1 can be prevented by a mutation which causes the loss of exon 9, and results in loss of function. Presenilins play a key role in the modulation of intracellular Ca2+ involved in presynaptic neurotransmitter release and long-term potentiation induction.

Dominant mutations in the genes that encode presenilin proteins are the most common cause of familial early-onset Alzheimer's disease.

Kallikriens are serine proteinases. The human tissue kallikrein gene family contains 15 members that play important roles in cancer. KLK6 has been implicated in Parkison's and Alzheimer's and shown be elevated in animal models of multiple sclerosis. KLK8 has been shown to be elevated in the hippocampus on Alzheimer’s patients’ brains and animal models of autoimmune encephalomyelitis

Matrix Metalloproteinases (MMPs) are a family of zinc metalloendopeptidases secreted by cells, and are responsible for much of the turnover of matrix components. They are produced as zymogens, with a signal sequence and propeptide segment that must be removed during activation. In general, This signal sequence and propeptide plus a catalytic domain (containing the highly conserved zinc binding site) characterizes the structure of the MMPs.

MMPs are considered to play an important role in wound healing, apoptosis, bone elongation, embryo development, uterine involution, angiogenesis and tissue remodeling, and in diseases such as multiple sclerosis, Alzheimer's, malignant gliomas, lupus, arthritis, periodontis, glumerulonephritis, atherosclerosis, tissue ulceration, and in cancer cell invasion and metastasis.

Caspases and Cathepsins are proteases involved in apoptosis. They also are implicated in cancer and other research areas.