Kallikreins are a subgroup of serine proteases, enzymes capable of cleaving peptide bonds in proteins. In humans, plasma kallikrein has no known paralogue, while tissue kallikrein-related peptidases (KLKs) encode a family of fifteen closely related serine proteases. These genes are localised to chromosome 19q13, forming the largest contiguous cluster of proteases within the human genome. Kallikreins are responsible for the coordination of various physiological functions including blood pressure, semen liquefaction and skin desquamation.
Maspin is a protein that in humans is encoded by the SERPINB5 gene. This protein belongs to the serpin superfamily. SERPINB5 was originally reported to function as a tumor suppressor gene in epithelial cells, suppressing the ability of cancer cells to invade and metastasize to other tissues. Furthermore, and consistent with an important biological function, Maspin knockout mice were reported to be non-viable, dying in early embryogenesis. However, a subsequent study using viral transduction as a method of gene transfer was not able to reproduce the original findings and found no role for maspin in tumour biology. Furthermore, the latter study demonstrated that maspin knockout mice are viable and display no obvious phenotype. These data are consistent with the observation that maspin is not expressed in early embryogenesis. The precise molecular function of maspin is thus currently unknown.
Kallikrein-1 is a protein that in humans is encoded by the KLK1 gene. KLK1 is a member of the peptidase S1 family.
Kallikrein-2 is a protein that in humans is encoded by the KLK2 gene, and is particularly associated with prostatic tissue.
Suppressor of tumorigenicity 14 protein, also known as matriptase, is a protein that in humans is encoded by the ST14 gene. ST14 orthologs have been identified in most mammals for which complete genome data are available.
Kallikrein-6 is a protein that in humans is encoded by the KLK6 gene. Kallikrein-6 is also referred to as neurosin, protease M, hK6, or zyme. It is a 223 amino acid sequence, derived from its 244 original form, which contains a 16 residue presignal and 5 residue activation peptide.
Kallikrein-5, formerly known as stratum corneum tryptic enzyme (SCTE), is a serine protease expressed in the epidermis. In humans it is encoded by the KLK5 gene. This gene is one of the fifteen kallikrein subfamily members located in a cluster on chromosome 19. Its expression is up-regulated by estrogens and progestins. Alternative splicing results in multiple transcript variants encoding the same protein.
Kallikrein-related peptidase 4 is a protein which in humans is encoded by the KLK4 gene.
Kallikrein-11 is a protein that in humans is encoded by the KLK11 gene.
Serpin B6 is a protein that in humans is encoded by the SERPINB6 gene.
Kallikrein-related peptidase 7 (KLK7) is a serine protease that in humans is encoded by the KLK7 gene. KLK7 was initially purified from the epidermis and characterised as stratum corneum chymotryptic enzyme (SCCE). It was later identified as the seventh member of the human kallikrein family, which includes fifteen homologous serine proteases located on chromosome 19 (19q13).
Transmembrane protease, serine 2 is an enzyme that in humans is encoded by the TMPRSS2 gene. It belongs to the TMPRSS family of proteins, whose members are transmembrane proteins which have a serine protease activity. The TMPRSS2 protein is found in high concentration in the cell membranes of epithelial cells of the lung and of the prostate, but also in the heart, liver and gastrointestinal tract.
Kallikrein-13 is a protein that in humans is encoded by the KLK13 gene.
Kallikrein-8 is a protein that in humans is encoded by the KLK8 gene.
Kallikrein-14 is a protein that in humans is encoded by the KLK14 gene.
Kallikrein-15 is a protein that in humans is encoded by the KLK15 gene.
Kallikrein-12 is a protein that in humans is encoded by the KLK12 gene.
Sialic acid-binding Ig-like lectin 9 is a protein that in humans is encoded by the SIGLEC9 gene.
Transmembrane protease, serine 6 is an enzyme that in humans is encoded by the TMPRSS6 gene.
Kallikrein-related peptidase 9 also known as KLK9 is an enzyme which in humans is encoded by the KLK9 gene.
