What is calmodulin control mechanism?
The principal function of calmodulin in smooth muscle is to activate crossbridge cycling and the development of force in response to a [Ca2+]i transient via the activation of myosin light-chain kinase and phosphorylation of myosin.
What is the function of activated calmodulin?
In neurons, calmodulin activates Ca2+/CaM-dependent protein kinase II (CaMKII), which allows for changes at the synapse that facilitate learning and memory. Calmodulin is also important for regulating cell proliferation and cell survival and can become dysregulated during cancer.
What happens when calcium binds to calmodulin?
When calcium is bound to calmodulin a helix-loop-helix is formed along the backbone and a conformational change occurs. This conformational change, coupled with the flexibility of the protein due to the flexible connecting linker, allows calmodulin to interact with and bind to a wide variety of other proteins.
What is calmodulin and how is it activated?
Calmodulin is a calcium-dependent protein required for the initiation of many different signaling pathways including long-term potentiation (LTP) and long-term depression (LTD) [26]. Calmodulin has two lobes, each of which can be independently activated by binding two calcium ions [27].
How does calmodulin help muscle contraction?
The overall result of this protein-protein interaction is a physiological effect, e.g., Ca2+ binding to calmodulin in smooth muscle allows it to interact with and activate myosin light chain kinase which catalyzes the phosphorylation of myosin. This reaction results in contraction of the smooth muscle.
What is the role of calmodulin in signal transduction pathways in plants?
The calmodulin (CaM) family is a major class of calcium sensor proteins which collectively play a crucial role in cellular signaling cascades through the regulation of numerous target proteins.
What does calmodulin do in cardiac muscle?
Calmodulin is involved in the control of the phosphorylation of the sarcoplasmic reticulum Ca2+ pump activator, phospholamban, thereby modulating the rate of Ca2+ uptake.
Does calmodulin bind to myosin?
Many unconventional myosins bind multiple calmodulin light chains and Ca2+, which can dramatically alter their mechanochemical and enzymatic activity. Calmodulin-binding myosins can also be regulated by phospholipid binding, phosphorylation of the heavy chain and actin-binding proteins.
What is the function of calmodulin in a cell?
Calmodulin Definition Calmodulin, or calcium-modulated protein, is a calcium-binding protein found in the cytoplasm of all eukaryotic cells. It interacts with many other proteins in the cell, and acts as a regulator or an effector molecule in a wide variety of cellular functions.
What is the role of calmodulin in PDE?
Calmodulin was initially identified in its role as an activator of cAMP PDE. In fact, calmodulin was first known as the calcium-dependent regulator protein of PDE. Since that time it has become clear that calmodulin is responsible for mediating the actions of calcium through a large variety of cellular processes.
How does calmodulin affect muscle contraction?
Another way that calmodulin affects muscle contraction is by controlling the movement of Ca 2+ across both the cell and sarcoplasmic reticulum membranes. The Ca 2+ channels, such as the ryanodine receptor of the sarcoplasmic reticulum, can be inhibited by calmodulin bound to calcium, thus affecting the overall levels of calcium in the cell.
Why is calmodulin a cooperative binding protein?
Calcium binding by calmodulin exhibits considerable cooperativity, making calmodulin an unusual example of a monomeric (single-chain) cooperative-binding protein. Furthermore, target binding alters the binding affinity of calmodulin toward Ca 2+ ions, which allows for complex allosteric interplay between Ca 2+ and target binding interactions.