Mutation of Aspartate 555 of the Sodium/Bicarbonate Transporter SLC4A4/NBCe1 Induces Chloride Transport.

ABSTRACT: To understand the mechanism for ion transport through the sodium/bicarbonate transporter SLC4A4 (NBCe1), we examined amino acid residues, within transmembrane domains, that are conserved among electrogenic Na/HCO(3) transporters but are substituted with residues at the corresponding site of all electroneutral Na/HCO(3) transporters. Point mutants were constructed and expressed in Xenopus oocytes to assess function using two-electrode voltage clamp. Among the mutants, D555E (charge-conserved substitution of the aspartate at position 555 with a glutamate) produced decreasing HCO(3)(-) currents at more positive membrane voltages. Immunohistochemistry showed D555E protein expression in oocyte membranes. D555E induced Na/HCO(3)-dependent pH recovery from a CO(2)-induced acidification. Current-v

SUBMITTER: Yang HS 

PROVIDER: S-EPMC2708891 | biostudies-literature | 2009 Jun

REPOSITORIES: biostudies-literature