Group:MUZIC:CapZ: Difference between revisions

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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 <references/>[http://www.ncbi.nlm.nih.gov/pubmed/12660160].

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 <references/>[http://www.ncbi.nlm.nih.gov/pubmed/12663865].

== Actin binding model == proposed by Narita ''et al'' <references/>[http://www.ncbi.nlm.nih.gov/pubmed/17110933]

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.

This two-step binding mechanism implies that the binding is possible even without the β-tentacle. This is because the first step alone fulfills two requirements for the barbed-end capping: the recognition of the barbed-end and the inhibition of polymerization and depolymerization.

[[Category: actin binding proteins, actin regulation, CapZ, actin capping protein]]

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 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 <references/>[http://www.ncbi.nlm.nih.gov/pubmed/12660160].
 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 <references/>[http://www.ncbi.nlm.nih.gov/pubmed/12663865].
+== Actin binding model == proposed by Narita ''et al'' <references/>[http://www.ncbi.nlm.nih.gov/pubmed/17110933]
+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.
+This two-step binding mechanism implies that the binding is possible even without the β-tentacle. This is because the first step alone fulfills two requirements for the barbed-end capping: the recognition of the barbed-end and the inhibition of polymerization and depolymerization.
 [[Category: actin binding proteins, actin regulation, CapZ, actin capping protein]]