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PDBsum entry 7cqh
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Signaling protein
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PDB id
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7cqh
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References listed in PDB file
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Key reference
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Title
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Calmodulin binds to drosophila trp with an unexpected mode.
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Authors
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W.Chen,
Z.Shen,
S.Asteriti,
Z.Chen,
F.Ye,
Z.Sun,
J.Wan,
C.Montell,
R.C.Hardie,
W.Liu,
M.Zhang.
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Ref.
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Structure, 2021,
29,
330.
[DOI no: ]
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PubMed id
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Abstract
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Drosophila TRP is a calcium-permeable cation channel essential for fly visual
signal transduction. During phototransduction, Ca2+ mediates both
positive and negative feedback regulation on TRP channel activity, possibly via
binding to calmodulin (CaM). However, the molecular mechanism underlying
Ca2+ modulated CaM/TRP interaction is poorly understood. Here, we
discover an unexpected, Ca2+-dependent binding mode between CaM and
TRP. The TRP tail contains two CaM binding sites (CBS1 and CBS2) separated by an
∼70-residue linker. CBS1 binds to the CaM N-lobe and CBS2 recognizes the CaM
C-lobe. Structural studies reveal the lobe-specific binding of CaM to
CBS1&2. Mutations introduced in both CBS1 and CBS2 eliminated CaM binding in
full-length TRP, but surprisingly had no effect on the response to light under
physiological conditions, suggesting alternative mechanisms governing
Ca2+-mediated feedback on the channel activity. Finally, we discover
that TRPC4, the closest mammalian paralog of Drosophila TRP, adopts a similar
CaM binding mode.
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