Calmodulin and calcium-release channels
Biol. Res
;
37(4): 577-582, 2004. ilus
Article
in English
| LILACS
| ID: lil-437511
ABSTRACT
Calmodulin (CaM) is a ubiquitous cytosolic protein that plays a critical role in regulating cellular functions by altering the activity of a large number of ion channels. There are many examples for CaM directly mediating the feedback effects of Ca2+ on Ca2+ channels. Recently the molecular mechanisms by which CaM interacts with voltage-gated Ca2+ channels, Ca2+-activated K+ channels and ryanodine receptors have been clarified. CaM plays an important role in regulating these ion channels through lobe-specific Ca2+ detection. CaM seems to behave as a channel subunit. It binds at low [Ca2+] and undergoes conformational changes upon binding of Ca2+, leading to an interaction with another part of the channel to regulate its gating. Here we focus on the mechanism by which CaM regulates the inositol 1,4,5-trisphosphate receptor (IP3R). Although the IP3R is inhibited by CaM and by other CaM-like proteins in the presence of Ca2+, we conclude that CaM does not act as the Ca2+ sensor for IP3R function. Furthermore we discuss a novel Ca2+-induced Ca2+-release mechanism found in A7r5 (embryonic rat aorta) and 16HBE14o- (human bronchial mucosa) cells for which CaM acts as a Ca2+ sensor.
Full text:
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Index:
LILACS (Americas)
Main subject:
Calmodulin
/
Calcium Channels
/
Endoplasmic Reticulum
/
Intracellular Membranes
Limits:
Animals
/
Humans
Language:
English
Journal:
Biol. Res
Journal subject:
Biology
Year:
2004
Type:
Article
Affiliation country:
Belgium
Institution/Affiliation country:
N+BE
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