Group:MUZIC:CapZ: Difference between revisions
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CapZ plays a role in targeting the actin filaments to other structural components. The sarcomeric isoform interacts with α-actinin and anchors the thin filament system to the Z-disk <ref>PMID:16416311</ref> | CapZ plays a role in targeting the actin filaments to other structural components. The sarcomeric isoform interacts with α-actinin and anchors the thin filament system to the Z-disk <ref>PMID:16416311</ref> | ||
Small interference RNA (siRNA) studies showed that knockdown of nebulin in chick skeletal myotubes leads to a reduction of assembled CapZ and a loss of the characteristic uniform alignment of the barbed ends of F-actin and this suggests that the interaction of Cap Z and nebulin plays a very important role in Z-disk architecture <ref>PMID:18272787</ref>. | Small interference RNA (siRNA) studies showed that knockdown of nebulin in chick skeletal myotubes leads to a reduction of assembled CapZ and a loss of the characteristic uniform alignment of the barbed ends of F-actin and this suggests that the interaction of Cap Z and nebulin plays a very important role in Z-disk architecture <ref>PMID:18272787</ref>. | ||
Cap Z regulates the activity of cardiac protein kinase C (PKC): down regulation of Cap Z leads to a decrease and alteration of the PKC signaling pathways. Cardiac Cap Z regulates binding of PKC II to the myofilaments with effects on cardiac contractility < | Cap Z regulates the activity of cardiac protein kinase C (PKC): down regulation of Cap Z leads to a decrease and alteration of the PKC signaling pathways. Cardiac Cap Z regulates binding of PKC II to the myofilaments with effects on cardiac contractility <ref>PMID:21257757</ref>. | ||
Other binding partners of Cap Z include the CARMIL protein which further interacts with Arp complex2/3 and myosin I, both of which are key players in actin based cell motility < | Other binding partners of Cap Z include the CARMIL protein which further interacts with Arp complex2/3 and myosin I, both of which are key players in actin based cell motility <ref>PMID:12660160</ref>. | ||
In vivo the capping of actin filaments is regulated by second messengers PIP and PIP 2 (Phosphatidylinositol 4,5-bisphosphate), upon signal transduction these molecules promote removal of Cap Z from actin filaments < | In vivo the capping of actin filaments is regulated by second messengers PIP and PIP 2 (Phosphatidylinositol 4,5-bisphosphate), upon signal transduction these molecules promote removal of Cap Z from actin filaments <ref>PMID:12663865</ref>. | ||
== Actin binding model == | == Actin binding model == | ||
Proposed by Narita ''et al'' < | Proposed by Narita ''et al'' <ref>PMID:17110933</ref> | ||
First, CP is attracted to the barbed-end of the actin filament through the electrostatic interactions between the basic residues, which are mainly but not exclusively on/around the α-tentacle and the acidic residues on the extreme surface at the barbed-end of the actin filament. The electrostatic interactions through the α-tentacle may be the major determining factors of the on-rate of the binding. This is because the deletion of the β-tentacle altered only the off-rate of the binding, without changing the on-rate. In contrast, the deletion of the a-tentacle reduced both the on- and off rates. | First, CP is attracted to the barbed-end of the actin filament through the electrostatic interactions between the basic residues, which are mainly but not exclusively on/around the α-tentacle and the acidic residues on the extreme surface at the barbed-end of the actin filament. The electrostatic interactions through the α-tentacle may be the major determining factors of the on-rate of the binding. This is because the deletion of the β-tentacle altered only the off-rate of the binding, without changing the on-rate. In contrast, the deletion of the a-tentacle reduced both the on- and off rates. | ||
Second, the β-tentacle finds the hydrophobic binding site on the front surface of actin. The binding of the b-tentacle acts as a lock, and thus reduces the off-rate as suggested previously. | Second, the β-tentacle finds the hydrophobic binding site on the front surface of actin. The binding of the b-tentacle acts as a lock, and thus reduces the off-rate as suggested previously. | ||
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==References== | ==References== | ||
<references/> | |||
[[Category: actin binding proteins, actin regulation, CapZ, actin capping protein]] | [[Category: actin binding proteins, actin regulation, CapZ, actin capping protein]] | ||
