title: alar4, a constitutive mutant of the A system for amino acid transport, has increased abundance of the Na+,K+-ATPase and mRNA for alpha 1 subunit of this enzyme.
abstract: A constitutive mutant, alar4, for the A system of amino acid transport, has increased activity and amount of the A system. This is accompanied by increased sensitivity to ouabain, as measured by efficiency of plating, and increased activity and abundance of the Na+,K+-ATPase that is present in the parental cell line, CHO-K1 (wild type). The latter was shown by increases in (i) ouabain-inhibitable 86Rb uptake in intact cells, (ii) ouabain-inhibitable ATPase activity in mixed membrane vesicles, and (iii) number of ouabain-binding sites and by similar Kd values for ouabain binding and K1/2 for ouabain inhibition of Na+,K+-ATPase as compared to the wild type. The increase in abundance of the Na+ pump is associated with a 4-fold increase in abundance of the mRNA for the alpha 1 subunit of the Na+,K+-ATPase. We could not detect mRNA for alpha 2 or alpha 3 or for the beta subunits. The increase in abundance of the A system and Na+,K+-ATPase is associated with a negligible increase in intracellular Na+ concentration. We propose that the increase in the abundance of the A system and the Na+,K+-ATPase is the result of a mutation in regulatory gene R1 that controls the A system and the Na+,K+-ATPase and is not due to a primary effect of a possible initial increase in Na+ concentration.
authors.affiliation: Department of Biological Sciences, University of California, Santa Barbara 93106.
authors.forename: N X
authors.initials: NX
authors.lastname: Qian
authors.forename: M
authors.initials: M
authors.lastname: Jones
authors.forename: A
authors.initials: A
authors.lastname: McDonough
authors.forename: E
authors.initials: E
authors.lastname: Englesberg
mesh_terms: D000596:Amino Acids / Q000378:metabolism*; D000818:Animals; D001692:Biological Transport; D002460:Cell Line; D002462:Cell Membrane / Q000201:enzymology; D015870:Gene Expression; D007700:Kinetics; D046911:Macromolecular Substances; D009154:Mutation; D010042:Ouabain / Q000494:pharmacology; D011188:Potassium / Q000378:metabolism; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics*; D012413:Rubidium / Q000378:metabolism; D012964:Sodium / Q000378:metabolism; D000254:Sodium-Potassium-Exchanging ATPase / Q000096:biosynthesis / Q000235:genetics*
chemical_list: D000596:Amino Acids; D046911:Macromolecular Substances; D012333:RNA, Messenger; D010042:Ouabain; D012964:Sodium; D000254:Sodium-Potassium-Exchanging ATPase; D012413:Rubidium; D011188:Potassium