Catalysis of the hydrolysis of peptide bonds in a polypeptide chain by a mechanism in which the sulfhydryl group of a cysteine residue at the active center acts as a nucleophile.
Through differential screening of established human leukaemia cell lines, we have identified and molecularly cloned lymphopain, a novel cysteine proteinase of the papain family. Lymphopain exhibits a remarkably restricted cellular pattern of expression, being predominantly expressed in cytotoxic T-lymphocytes and natural killer cells. The human lymphopain locus maps to chromosome 11q13, encodes a polypeptide of 376 amino acids and is conserved in the mouse. Both human and murine forms appear more closely related to protozoan papain-like enzymes than to other mammalian members of the papain family. The cellular distribution of lymphopain expression, together with the functional demonstration of lymphopain-associated proteinase activity in vitro, is suggestive of a role for lymphopain in immune cell-mediated, cell killing.
Enzyme which catalyzes hydrolysis reaction, i.e. the addition of the hydrogen and hydroxyl ions of water to a molecule with its consequent splitting into two or more simpler molecules.
Proteolytic enzyme with a cysteine residue (Cys) in its active site. There are many families of thiol proteases. The most well known one is the papain family (C1 in MEROPS classification) which is known to exist in most eukaryotes.
A reference proteome is a set of protein sequences derived from a complete proteome which constitutes a defined standard for a particular user community. Reference proteomes are manually defined according to a number of criteria. They cover the proteomes of well- studied model organisms and other proteomes of interest for biomedical and biotechnological research. Reference proteomes have been selected to provide broad coverage of the tree of life, and constitute a representative cross-section of the taxonomic diversity to be found within UniProtKB.