Editing Calmodulin (section)

=== Specific examples ===

==== Role in smooth muscle contraction ====
[[File:Calmodulin bound to MLC Kinase.jpg|thumb|Calmodulin bound to a peptide from MLC kinase ({{PDB|2LV6}})]]
Calmodulin plays an important role in [[Excitation contraction coupling|excitation contraction (EC) coupling]] and the initiation of the cross-bridge cycling in [[Smooth muscle tissue|smooth muscle]], ultimately causing smooth muscle contraction.<ref name="Tansey-1994">{{cite journal | vauthors = Tansey MG, Luby-Phelps K, Kamm KE, Stull JT | title = Ca(2+)-dependent phosphorylation of myosin light chain kinase decreases the Ca2+ sensitivity of light chain phosphorylation within smooth muscle cells | journal = The Journal of Biological Chemistry | volume = 269 | issue = 13 | pages = 9912–20 | date = April 1994 | doi = 10.1016/S0021-9258(17)36969-7 | pmid = 8144585 | url = http://www.jbc.org/content/269/13/9912 | doi-access = free }}</ref> In order to activate contraction of smooth muscle, the head of the [[myosin light chain]] must be phosphorylated. This phosphorylation is done by [[Myosin light-chain kinase|myosin light chain (MLC) kinase]]. This MLC kinase is activated by a calmodulin when it is bound by calcium, thus making smooth muscle contraction dependent on the presence of calcium, through the binding of calmodulin and activation of MLC kinase.<ref name="Tansey-1994" />

Another way that calmodulin affects muscle contraction is by controlling the movement of Ca<sup>2+</sup> across both the cell and [[sarcoplasmic reticulum]] membranes. The [[Calcium channels|Ca<sup>2+</sup> 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.<ref>{{cite journal | vauthors = Walsh MP | s2cid = 2304136 | title = Calmodulin and the regulation of smooth muscle contraction | journal = Molecular and Cellular Biochemistry | volume = 135 | issue = 1 | pages = 21–41 | date = June 1994 | pmid = 7816054 | doi = 10.1007/bf00925958 }}</ref> Calcium pumps take calcium out of the cytoplasm or store it in the [[endoplasmic reticulum]] and this control helps regulate many downstream processes.

This is a very important function of calmodulin because it indirectly plays a role in every physiological process that is affected by [[Smooth muscle tissue|smooth muscle]] contraction such as digestion and contraction of arteries (which helps distribute blood and regulate [[blood pressure]]).<ref>{{cite journal | vauthors = Martinsen A, Dessy C, Morel N | title = Regulation of calcium channels in smooth muscle: new insights into the role of myosin light chain kinase | journal = Channels | volume = 8 | issue = 5 | pages = 402–13 | date = 2014-10-31 | pmid = 25483583 | pmc = 4594426 | doi = 10.4161/19336950.2014.950537 }}</ref>

==== Role in metabolism ====
Calmodulin plays an important role in the activation of [[phosphorylase kinase]], which ultimately leads to [[glucose]] being cleaved from [[glycogen]] by [[glycogen phosphorylase]].<ref name="Nishizawa-1988">{{cite journal | vauthors = Nishizawa Y, Okui Y, Inaba M, Okuno S, Yukioka K, Miki T, Watanabe Y, Morii H | display-authors = 6 | title = Calcium/calmodulin-mediated action of calcitonin on lipid metabolism in rats | journal = The Journal of Clinical Investigation | volume = 82 | issue = 4 | pages = 1165–72 | date = October 1988 | pmid = 2844851 | pmc = 442666 | doi = 10.1172/jci113713 }}</ref>

Calmodulin also plays an important role in [[lipid metabolism]] by affecting [[Calcitonin gene-related peptide|calcitonin]]. Calcitonin is a polypeptide hormone that lowers blood Ca<sup>2+</sup> levels and activates [[G protein|Gs protein]] cascades that leads to the generation of cAMP. The actions of calcitonin can be blocked by inhibiting the actions of calmodulin, suggesting that calmodulin plays a crucial role in the activation of calcitonin.<ref name="Nishizawa-1988" />

==== Role in short-term and long-term memory ====
[[Ca2+/calmodulin-dependent protein kinase II|Ca<sup>2+</sup>/calmodulin-dependent protein kinase II]] (CaMKII) plays a crucial role in a type of synaptic plasticity known as [[long-term potentiation]] (LTP) which requires the presence of calcium/calmodulin. CaMKII contributes to the [[phosphorylation]] of an [[AMPA receptor]] which increases the sensitivity of AMPA receptors.<ref name="Lledo-1995">{{cite journal | vauthors = Lledo PM, Hjelmstad GO, Mukherji S, Soderling TR, Malenka RC, Nicoll RA | title = Calcium/calmodulin-dependent kinase II and long-term potentiation enhance synaptic transmission by the same mechanism | journal = Proceedings of the National Academy of Sciences of the United States of America | volume = 92 | issue = 24 | pages = 11175–9 | date = November 1995 | pmid = 7479960 | pmc = 40594 | doi = 10.1073/pnas.92.24.11175 | bibcode = 1995PNAS...9211175L | doi-access = free }}</ref> Furthermore, research shows that inhibiting CaMKII interferes with LTP.<ref name="Lledo-1995" />