Effects of Ca2+, theophylline and promethazine on protein phosphorylation in intact cells of rabbit ileum Correlation with active Na and Cl absorption

Geoffrey W.G. Sharp, Cynthia Hannah-White, Marwan El-Sabban, Michael E. Cohen, Mark Donowitz

Research output: Contribution to journalArticle


The effects of Ca2+, theophylline and promethazine on the phosphorylation of microvillus membrane proteins have been studied in rabbit ileal epithelial cells, using intact cell phosphorylation techniques followed by purification of microvillus membranes, separation of peptides by two-dimensional polyacrylamide gel electrophoresis, and quantitation of phosphorylation by computerized densitometry of autoradiograms. The Ca2+ ionophore A23187 caused increased phosphorylation of four and possibly five polypeptides; theophylline increased phosphorylation of three peptides, two of which had the same Mr and pI values as the peptides altered by the Ca2+ ionophore; promethazine decreased the phosphorylation of one of the peptides increased by Ca2+ ionophore. The phosphorylated peptides, which respond similarly to more than one agent which affect ileal Na and Cl absorption, could be involved in the regulation of NaCl absorption either as transport proteins or regulators of transport proteins.

Original languageEnglish (US)
Pages (from-to)309-314
Number of pages6
JournalFEBS Letters
Issue number2
StatePublished - Sep 14 1987
Externally publishedYes



  • (Rabbit intestine)
  • Ca calmodulin-dependent protein kinase
  • Electrolyte absorption
  • Phosphorylation
  • cyclic AMP-dependent protein kinase

ASJC Scopus subject areas

  • Biophysics
  • Structural Biology
  • Biochemistry
  • Molecular Biology
  • Genetics
  • Cell Biology

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