Group:MUZIC:CapZ
From Proteopedia
CapZ (Actin Capping Protein)
CapZ is expressed in all eukaryotic cells. It binds to the fast growing barbed ends of actin filaments and blocks G-actin association and disassociation, thus regulating actin filament dynamics. In skeletal muscle it localizes at the Z-disk. Cap Z is a heterodimer composed of two subunits α and β and there are at least two isoforms of each of the subunits. In cardiomyocites the β1 containing isoform localizes to the Z-disk and β2 containing isoform localizes to the cell periphery and intercalated disc. The crystal structure of the sarcomeric form has been resolved to a resolution of 2.1 Å by X-ray crystallography (1IZN). [1]
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Template:ABSTRACT PUBMED 12660160
Structure
Cap Z was shown to be a stable heterodimer with α and β subunits of 286 and 277 residues, respectively. It is a mixed α-helix and β-sheet protein. CapZ has an elongated structure, with overall dimensions of~90 x 50 x55 Å. The capZ dimer has a pseudo two-fold symmetry, with the monomers joining together to form a central 10-stranded antiparallel . This creates an elongated molecule with the N- and C-terminus of each monomer on opposite faces of the central β -sheet. The C-termini of the subdomains are at opposite ends of the elongated molecule. One Cap Z heterodimer appears to be able to bind two actin molecules; this may explain why it is selective for the F-actin barbed end as opposed to monomeric G-actin. Cap Z is thought to bind between actin subdomains 1 and 3 (the barbed-end). Cap Z also binds a spectrin domain of α-actinin and the C-terminus of nebulin [2].
