Calmodulin and Calcium-release Channels
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 mechanis...
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| Autores principales: | , , , , |
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| Lenguaje: | English |
| Publicado: |
Sociedad de Biología de Chile
2004
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| Materias: | |
| Acceso en línea: | http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0716-97602004000400011 |
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| Sumario: | 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 |
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