Final answer:
Ca2+ binds calmodulin in a 1:1 stoichiometric ratio, activating Ca2+/calmodulin-dependent (CaM) kinases as part of a cellular signaling pathway that includes enzymes like myosin light chain kinase.
Step-by-step explanation:
The Ca2+ released in calmodulin activation binds calmodulin in a 1:1 stoichiometric ratio, which activates Ca2+/calmodulin-dependent (CaM) kinases.
Specifically, this calcium binding to calmodulin is crucial for the activation of various cellular enzymes, including myosin light chain kinase involved in muscle contraction and CaM kinases that phosphorylate several target proteins, leading to diverse cell-specific responses.
When inositol triphosphate (IP3) binds to its receptors on the smooth endoplasmic reticulum, it prompts the release of Ca2+ into the cytoplasm.
This influx of Ca2+ activates several enzymes through molecules like calmodulin.
The Ca2+-calmodulin complex can then activate CaM kinases, which play a pivotal role in the cellular signaling pathways, especially in the regulation of calcium ion concentration within the cell and subsequent enzyme activation for various physiological processes.