Members of the NSCC2 family have been sequenced from various yeast, fungal and animals species including Saccharomyces cerevisiae, Drosophila melanogaster and Homo sapiens. These proteins are the Sec62 proteins, believed to be associated with the Sec61 and Sec63 constituents of the general protein secretary systems of yeast microsomes. They are also the non-selective cation (NS) channels of the mammalian cytoplasmic membrane. The yeast Sec62 protein has been shown to be essential for cell growth. The mammalian NS channel proteins have been implicated in platelet derived growth factor(PGDF) dependent single channel current in fibroblasts. These channels are essentially closed in serum deprived tissue-culture cells and are specifically opened by exposure to PDGF. These channels are reported to exhibit equal selectivity for Na+, K+ and Cs+ with low permeability to Ca2+, and no permeability to anions.
Members of the NSCC2 family have been sequenced from various fungal and animal species including Saccharomyces cerevisiae, Drosophila melanogaster and Homo sapiens. These proteins are the Sec62 proteins, believed to be associated with the Sec61 and Sec63 constituents of the general protein secretary systems of yeast microsomes. They are also the non-selective cation (NS) channels of the mammalian cytoplasmic membrane. The yeast Sec62 protein has been shown to be essential for cell growth. The mammalian NS channel proteins have been implicated in platelet derived growth factor(PGDF) dependent single channel current in fibroblasts. These channels are essentially closed in serum deprived tissue-culture cells and are specifically opened by exposure to PDGF. These channels are reported to exhibit equal selectivity for Na+, K+ and Cs+ with low permeability to Ca2+, and no permeability to anions.This family of Sec62 proteins is restricted to the Ascomycota.
In Saccharomyces cerevisiae, Sec63 is a component of the Sec62/63 complex (includes Sec63p, Sec62p, Sec66p and Sec72p), which is involved in SRP-independent post-translational translocation across the endoplasmic reticulum (ER) and functions together with the Sec61 complex and KAR2 in a channel-forming translocon complex []. In humans, Sec63 is part of the multicomponent translocon that contains the trimeric SEC61 complex, SEC62 and SEC63. It is required for integral membrane and secreted preprotein translocation across the endoplasmic reticulum membrane [, ].Defects in SEC63 are a cause of polycystic liver disease (PCLD). PCLD is an autosomal dominant disorder and is characterised by the presence of multiple liver cysts of biliary epithelial origin [].
