Inhibition of inositol phosphate second messenger formation by intracellular loop one of a human calcitonin receptor. Expression and mutational analysis of synthetic receptor genes

Daniel R. Nussenzveig, Colette N. Thaw, Marvin C. Gershengorn

Research output: Contribution to journalArticle

78 Scopus citations

Abstract

Receptors for calcitonin (CTRs) have been cloned from several species, and two isoforms have been found to be expressed in human tissue. One human CTR isoform (hCTR-1) contains a 16-amino acid insertion in its first intracellular (11) loop that is not present in porcine CTR (pCTR), rat CTR, or the other human CTR (hCTR-2). To facilitate the study of CTRs by mutational analysis, we have constructed synthetic hCTR-1 and hCTR-2 genes. Activation of hCTR-1 expressed transiently in COS-1 cells stimulates the formation of cAMP but not of inositol phosphates (IPs) whereas pCTR, a chimeric CTR in which the 11 loop of pCTR was substituted for the 11 loop of hCTR-1, and hCTR-2 stimulate cAMP and IP formation. A series of chimeric CTRs in which intracellular loops 1, 2, and 3 and the carboxyl tail of pCTR were substituted individually or in combination for those of hCTR-1 were constructed. All chimeras stimulated cAMP formation whereas chimeras containing the 11 loop of hCTR-1 with its 16-amino acid insertion were incapable of stimulating IP formation. There was no correlation between maximal stimulation of cAMP and IP formation by these CTRs. Thus, an inserted sequence in the 11 loop of hCTR-1 abolishes stimulation of the IP signal transduction pathway while allowing stimulation of the cAMP pathway.

Original languageEnglish (US)
Pages (from-to)28123-28129
Number of pages7
JournalJournal of Biological Chemistry
Volume269
Issue number45
StatePublished - Jan 1 1994

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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