title: Evidence for an interaction between adducin and Na(+)-K(+)-ATPase: relation to genetic hypertension.
abstract: Adducin point mutations are associated with genetic hypertension in Milan hypertensive strain (MHS) rats and in humans. In transfected cells, adducin affects actin cytoskeleton organization and increases the Na(+)-K(+)-pump rate. The present study has investigated whether rat and human adducin polymorphisms differently modulate rat renal Na(+)-K(+)-ATPase in vitro. We report the following. 1) Both rat and human adducins stimulate Na(+)-K(+)-ATPase activity, with apparent affinity in tens of nanomolar concentrations. 2) MHS and Milan normotensive strain (MNS) adducins raise the apparent ATP affinity for Na(+)-K(+)-ATPase. 3) The mechanism of action of adducin appears to involve a selective acceleration of the rate of the conformational change E(2) (K) --> E(1) (Na) or E(2)(K). ATP --> E(1)Na. ATP. 4) Apparent affinities for mutant rat and human adducins are significantly higher than those for wild types. 5) Recombinant human alpha- and beta-adducins stimulate Na(+)-K(+)-ATPase activity, as do the COOH-terminal tails, and the mutant proteins display higher affinities than the wild types. 6) The cytoskeletal protein ankyrin, which is known to bind to Na(+)-K(+)-ATPase, also stimulates enzyme activity, whereas BSA is without effect; the effects of adducin and ankyrin when acting together are not additive. 7) Pig kidney medulla microsomes appear to contain endogenous adducin; in contrast with purified pig kidney Na(+)-K(+)-ATPase, which does not contain adducin, added adducin stimulates the Na(+)-K(+)-ATPase activity of microsomes only about one-half as much as that of purified Na(+)-K(+)-ATPase. Our findings strongly imply the existence of a direct and specific interaction between adducin and Na(+)-K(+)-ATPase in vitro and also suggest the possibility of such an interaction in intact renal membranes.
authors.affiliation: Prassis Research Institute Sigma-Tau, 20019 Settimo Milanese, Italy.
authors.forename: M
authors.initials: M
authors.lastname: Ferrandi
authors.forename: S
authors.initials: S
authors.lastname: Salardi
authors.forename: G
authors.initials: G
authors.lastname: Tripodi
authors.forename: P
authors.initials: P
authors.lastname: Barassi
authors.forename: R
authors.initials: R
authors.lastname: Rivera
authors.forename: P
authors.initials: P
authors.lastname: Manunta
authors.forename: R
authors.initials: R
authors.lastname: Goldshleger
authors.forename: P
authors.initials: P
authors.lastname: Ferrari
authors.forename: G
authors.initials: G
authors.lastname: Bianchi
authors.forename: S J
authors.initials: SJ
authors.lastname: Karlish
mesh_terms: D000818:Animals; D017487:Ankyrins / Q000494:pharmacology; D002148:Calmodulin-Binding Proteins / Q000235:genetics / Q000302:isolation & purification / Q000494:pharmacology / Q000502:physiology*; D004912:Erythrocytes / Q000201:enzymology / Q000378:metabolism; D006801:Humans; D006973:Hypertension / Q000235:genetics* / Q000378:metabolism*; D007668:Kidney / Q000201:enzymology / Q000378:metabolism; D009154:Mutation / Q000502:physiology; D051381:Rats; D011919:Rats, Inbred Strains; D011994:Recombinant Proteins / Q000494:pharmacology; D012710:Serum Albumin, Bovine / Q000494:pharmacology; D000254:Sodium-Potassium-Exchanging ATPase / Q000302:isolation & purification / Q000378:metabolism / Q000502:physiology*; D000099291:Adducins
chemical_list: D017487:Ankyrins; D002148:Calmodulin-Binding Proteins; D011994:Recombinant Proteins; D012710:Serum Albumin, Bovine; D000254:Sodium-Potassium-Exchanging ATPase; D000099291:Adducins