Members of the Non-Selective Cation Channel-2 (NSCC2) Family
TC#1.A.15
have been sequenced from various yeast, fungal and animals species including ''

Saccharomyces cerevisiae ''Saccharomyces cerevisiae'' () (brewer's yeast or baker's yeast) is a species of yeast (single-celled fungal microorganisms). The species has been instrumental in winemaking, baking, and brewing since ancient times. It is believed to have be ...

'', ''

Drosophila melanogaster ''Drosophila melanogaster'' is a species of fly (an insect of the Order (biology), order Diptera) in the family Drosophilidae. The species is often referred to as the fruit fly or lesser fruit fly, or less commonly the "vinegar fly", "pomace fly" ...

'' and ''

Homo sapiens Humans (''Homo sapiens'') or modern humans are the most common and widespread species of primate, and the last surviving species of the genus ''Homo''. They are Hominidae, great apes characterized by their Prehistory of nakedness and clothing ...

''. These proteins are the Sec62 proteins, believed to be associated with the Sec61 and Sec63 constituents of the general protein secretory systems of yeast microsomes. They are also the non-selective (NS) cation channels of the mammalian cytoplasmic membrane.

Function

NSCC2 channels are believed to provide entry pathways in response to

growth factor A growth factor is a naturally occurring substance capable of stimulating cell proliferation, wound healing, and occasionally cellular differentiation. Usually it is a secreted protein or a steroid hormone. Growth factors are important for ...

s. 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 Platelet-derived growth factor (PDGF) is one among numerous growth factors that regulate cell growth and division. In particular, PDGF plays a significant role in blood vessel formation, the growth of blood vessels from already-existing blood ...

(PDGF)-dependent single channel current in

fibroblast A fibroblast is a type of cell (biology), biological cell typically with a spindle shape that synthesizes the extracellular matrix and collagen, produces the structural framework (Stroma (tissue), stroma) for animal Tissue (biology), tissues, and ...

s. These channels are essentially closed in serum deprived tissue-culture cells and are specifically opened by exposure to PDGF. The channels are reported to exhibit equal selectivity for Na⁺ , K⁺ and Cs⁺ with low permeability to Ca²⁺ , and no permeability to anions. Channel open probability is voltage- and cytoplasmic Ca²⁺-independent.

Transport reaction

The generalized transport reaction catalyzed by members of the NSCC2 family is: : Cation (out) ⇌ cation (in)

Structure and location

Sequenced NSCC2 family proteins are 283-402 amino acyl residues in length and exhibit two putative transmembrane α-helical segments (TMSs). The ''S. cerevisiae'' protein, of 283 amino acyl residues, has cytoplasmic N- and C-termini with two putative TMSs at positions 159-178 and 193-213. The C-terminal 25 residues are rich in arginine and lysine. These proteins have been reported to be present in both endoplasmic reticular and cytoplasmic membranes.

References

{{CCBYSASource, sourcepath=http://www.tcdb.org/search/result.php?tc=1.a.15, sourcearticle=1.A.15 The Non-selective Cation Channel-2 (NSCC2) Family, revision=699838558 Protein families Membrane proteins Transmembrane proteins Transmembrane transporters Transport proteins Integral membrane proteins