Detection of calcium-dependent regulatory protein binding components using 125I-labeled calcium-dependent regulatory protein

D. C. LaPorte, D. R. Storm

Research output: Contribution to journalArticlepeer-review

32 Scopus citations


The calcium-dependent regulatory protein (CDR) purified from bovine brain was iodinated with Na[125I]I using the lactoperoxidase-glucose oxidase system. The iodinated protein retained its ability to stimulate the Ca2+-sensitive CDR-depleted cyclic nucleotide phosphodiesterase from bovine heart. Stimulation of the phosphodiesterase by 125I-CDR was Ca2+-dependent and the labeled protein had a K(a) for activation of cyclic nucleotide phosphodiesterase that was 4 times greater than unmodified CDR. 125I-CDR formed a Ca2+-dependent complex with the partially purified cyclic nucleotide phosphodiesterase which was detectable by autoradiography following electrophoresis of the complex on nondenaturing gels. This technique was used to detect CDR binding components in crude homogenates prepared from bovine heart and brain.

Original languageEnglish (US)
Pages (from-to)3374-3377
Number of pages4
JournalJournal of Biological Chemistry
Issue number10
StatePublished - 1978

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