cDNA cloning and localization of a band 3-related protein from ileum

Am J Physiol. 1992 Sep;263(3 Pt 1):G345-52. doi: 10.1152/ajpgi.1992.263.3.G345.

Abstract

A Cl(-)-HCO3- exchanger in the brush-border membrane mediates active Cl- absorption and regulates intracellular pH in rabbit ileum. The molecular identity of the ileal Cl(-)-HCO3- exchanger has not been established. The best-characterized plasma membrane Cl(-)-HCO3- exchanger is erythroid band 3. Structurally related proteins in nonerythroid tissues comprise an anion exchanger (AE) family. We used the polymerase chain reaction to amplify and clone a cDNA encoding an ileal band 3-related protein (B3RP) from rabbit ileal enterocytes. The composite sequence is 3,909 bp and is predicted to encode a protein of 136 kDa. The deduced amino acid sequence is 95% identical to murine renal AE2, indicating that ileal B3RP is rabbit AE2. Antisera generated against a cytoplasmic fragment of ileal B3RP recognized a 160- to 170-kDa polypeptide in the brush-border membrane, but not the basolateral membrane, of ileal crypt and villus enterocytes. This correlates with previous studies indicating that a Cl(-)-HCO3- exchange is present in brush-border but not basolateral membrane vesicles from rabbit ileal enterocytes. We conclude that ileal B3RP is a product of the AE gene family, and is present in the brush-border of ileal enterocytes, where it may mediate Cl(-)-HCO3- exchange.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Anion Exchange Protein 1, Erythrocyte / genetics
  • Anion Exchange Protein 1, Erythrocyte / metabolism*
  • Base Sequence
  • Cloning, Molecular*
  • DNA / genetics*
  • Ileum / cytology
  • Ileum / metabolism*
  • Immunoblotting
  • Male
  • Molecular Sequence Data
  • Rabbits
  • Tissue Distribution
  • Transcription, Genetic

Substances

  • Anion Exchange Protein 1, Erythrocyte
  • DNA

Associated data

  • GENBANK/S37423
  • GENBANK/S44552
  • GENBANK/S45791
  • GENBANK/S45856