Biochemical analysis of the membrane topology of the amiloride-sensitive Na+ channel

摘要: A key protein component of the amiloride-sensitive sodium channel has been cloned from rat colon and human lung. It may represent first member a new family ionic channels expressed nematode to human. The biochemical properties protein, 699 amino acids long polypeptide, have analyzed. Four polyclonal antibodies raised against distinct parts immunoprecipitated glycosylated 96 kDa after cRNA expression in oocytes as well vitro translation. When alone into oocytes, was not stable; most it remains stacked endoplasmic reticulum. This results very low yield complete maturation at cell surface pure cRNA. To determine membrane topology translation by rabbit reticulocyte lysate performed followed insertion canine pancreatic microsomes protease digestion. Analysis revealed model with only two transmembrane alpha helices large extracellular domain about 500 acids. NH2 COOH termini are cytoplasmic. Protease digestion suggest possible presence structural element that could function similar H5 segment K+ channels. indicates there is no cytoplasmic site for kinase phosphorylation. known regulation activity hormones activate this such vasopressin might thus be situated on another component.