Molecular size of the Na+-H+ antiport in renal brush border membranes, as estimated by radiation inactivation

Journal Article · Fri Apr 15 04:00:00 EDT 1988 · Biochem. Biophys. Res. Commun.; (United States)

DOI:https://doi.org/10.1016/S0006-291X(88)80739-3· OSTI ID:6998025

Beliveau, R; Demeule, M; Potier, M

The radiation inactivation method was applied to brush border membrane vesicles from rat kidney, in order to estimate the molecular size of the Na+-H+ antiporter. Sodium influx (1mM) driven by an acid intravesicular pH was unaffected by the high osmolarity of the cryoprotective solution. Initial rate of influx was estimated by linear regression performed on the first 10 seconds of transport: 0.512 pmol/micrograms protein/s. There was no binding component involved. Incubation performed in the presence of 1 mM amiloride, an inhibitor of the Na+-H+ antiport gave an initial rate of only 0.071 pmol/microgram/s, an 82% inhibition. Membrane vesicles were irradiated at -78 degrees C in a Gammacel Model 220. Sodium influx was reduced, as the dose of radiation increased, but the influx remained linear for the period of time (10s) during which the initial rate was estimated, indicating no alteration of the proton driving force during this time period. Amiloride-insensitive flux remained totally unaffected by the radiation dose, indicating that the passive permeability of the membrane towards sodium was unaffected. The amiloride-sensitive pathway presented a monoexponential profile of inactivation, allowing the molecular size to be estimated at 321 kDa. Based on DCCD-binding studies suggesting the molecular size of the monomer to be around 65 kDa for rat kidney, our results suggest that the functional transporter in the membrane to be a multimer.

• Research Organization: Groupe de Recherche en Transport Membranaire (Univ. Montreal), Quebec (Canada)
• OSTI ID: 6998025
• Journal Information: Biochem. Biophys. Res. Commun.; (United States), Journal Name: Biochem. Biophys. Res. Commun.; (United States) Vol. 152:1; ISSN BBRCA
• Country of Publication: United States
• Language: English

Related Subjects

560120* -- Radiation Effects on Biochemicals
Cells
& Tissue Culture
63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
ALKALI METALS
ANIMALS
BARYONS
BIOLOGICAL EFFECTS
BIOLOGICAL RADIATION EFFECTS
BODY
CELL CONSTITUENTS
CELL MEMBRANES
ELEMENTARY PARTICLES
ELEMENTS
FERMIONS
HADRONS
IRRADIATION
KIDNEYS
MAMMALS
MEMBRANE TRANSPORT
MEMBRANES
METALS
MOLECULAR WEIGHT
NUCLEONS
ORGANS
PERMEABILITY
PROTONS
RADIATION EFFECTS
RATS
RODENTS
SODIUM
VERTEBRATES