Anti-PCSK7 antibody (ab47925)

Relevance

PC7 was the first described in the rat pituitary, and found to be expressed in many tissues including brain, adrenal gland, gut, ovary, testis, kidney, liver lung, thyroid and pancreas. A literature alias is C8 or PC8 . Two splice variants are reported; a 591 amino acid sequence (PC7A) and a 785 amino acid membrane-associated form (PC7B). The longer form is thought to be bound in the Golgi, and the shorter form secreted through dense core secretory granules. PC7 has been shown to cleave parathyroid hormone and Tumor Necrosis Factor aloha converting enzyme (TACE, ADAM17). Like furin, PC1, PC2 and PACE4, PC7 is a serine proteinase that cleaves after pairs of basic amino acids, but with some differences in substrate specificity and distribution. The catalytic domain has homology to other PC enzymes, the prohormone convertase family initially discovered for their role in processing POMC, insulin and other pro-hormones, and later found to process a wider range of precursor proteins. Some have renamed the prohormone convertases as proprotein convertases, and another group has renamed the entire family with a uniform nomenclature of SPCs (subtilisin-like proprotein convertases), with PC7 getting the SPC7 moniker. PC7 structure contains a propeptide domain, a catalytic domain and an RGD containing cysteine-rich domain (homo-B). The longer sequence contains an extended cysteine-rich domain. The PCs have an RxxR consensus cleavage requirement, and the propeptide is separated from the mature protein by just such a sequence. After cleavage of the propeptide domain, PC7 becomes a two-chain form, and the propeptide piece is released after a second internal cleavage. PC7A resides mainly in the dense core secretory vesicles and the TGN, and is cycled to the surface, with some of the PC7 being secreted from the cells. PC7 has been reported to be elevated in tumor cell lines and to increase tumor progression. The message for PC7A encodes a 591 amino acid protein with a predicted mass of 64.4 kDa, and a pI of 5.9. The PC7B protein has an apparent mass of 101 kDa on reduced SDS PAGE gels, and is processed to a secreted 89 kDa form.

Cellular localization

The longer form is thought to be bound in the Golgi, and the shorter form secreted through dense core secretory granules.

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