Two putative light-sensitive ion channels have been isolated from Drosophila, encoded by the transient-receptor-potential (trp) and transient-receptor-potential-like (trpl) genes. The cDNA encoding the Trpl protein was initially isolated on the basis that the expressed protein binds calmodulin. Using both fusion proteins and a synthetic peptide, we now show that two calmodulin-binding sites are present in the C-terminal domain of the Trpl protein, CBS-1 and CBS-2. CBS-1 binds calmodulin in a Ca2+-dependent fashion, requiring Ca2+ concentrations above 0.3-0.5 μM for calmodulin binding. In contrast, CBS-2 binds the Ca2+-free form of calmodulin, with dissociation occurring at Ca2+ concentrations between 5 and 25 μM. Phosphorylation of a serine residue within a peptide encompassing CBS-1 by cyclic AMP-dependent protein kinase (PKA) abolishes calmodulin binding, and phosphorylation of the adjacent serine by protein kinase C appears to modulate this phosphorylation by PKA. Interpretation of these findings provides a novel model for ion-channel gating and modulation in response to changing levels of intracellular Ca2+.

Item Type:	Refereed Article
Keywords:	calcium ion; calmodulin binding protein; complementary DNA; cyclic AMP dependent protein kinase; hybrid protein; ion channel; article; binding site; channel gating; Drosophila melanogaster; nonhuman; priority journal; protein analysis
Research Division:	Biological Sciences
Research Group:	Biochemistry and cell biology
Research Field:	Signal transduction
Objective Division:	Expanding Knowledge
Objective Group:	Expanding knowledge
Objective Field:	Expanding knowledge in the biological sciences
UTAS Author:	Warr, CG (Professor Coral Warr)
ID Code:	131996
Year Published:	1996
Web of Science® Times Cited:	75
Deposited By:	Office of the School of Medicine
Deposited On:	2019-04-16
Last Modified:	2019-04-16
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