CAPZA2
Description
The CAPZA2 (capping actin protein of muscle Z-line subunit alpha 2) is a protein-coding gene located on chromosome 7.
CapZ-alpha2, encoded by the CAPZA2 gene, is a 33.0 kDa protein with 286 amino acids. It's located on chromosome 7, position q31.2-q31.3. This protein contains three critical leucines for actin binding, and is 85% identical to CapZ-alpha1. It's expressed in various tissues, including muscle, where it caps actin at Z-discs. The ratio of CapZ-alpha2 to CapZ-alpha1 varies depending on the tissue. CapZ binds to the barbed end of actin filaments, preventing the addition or loss of actin monomers. It plays a role in organizing myofilaments during myofibrillogenesis and is present at Z-discs before actin filament striation, potentially directing the polarity and organization of sarcomeric actin during I-band formation. The calcium-binding protein S100A may modulate CapZ-alpha2 function in muscle tissues, as it interacts with the protein's C-terminal region in the presence of calcium. CapZ appears to regulate intracellular signaling of contractile proteins in cardiac muscle.
F-actin-capping proteins, like CAPZA2, bind to the fast-growing ends of actin filaments (barbed ends) without requiring calcium. This binding prevents the addition or removal of actin monomers at these ends. Unlike other capping proteins such as gelsolin and severin, CAPZA2 does not break apart actin filaments.
CAPZA2 is also known as CAPPA2, CAPZ.
