Identification of Proteins Interacting with the Alpha Subunits of Actin Capping Protein

Actin is one of the three major filaments of the cytoskeleton that is involved in a number of cellular processes including cell motility, organelle movement, and cell division. Actin is regulated by a number of accessory proteins, including actin capping protein (CP). CP is used to regulate the addition of monomers at the barbed end of the actin filament. CP is composed of two subunits, an alpha and a beta. Three isoforms for each subunit have been identified (α1, α2, α3, β1, β2, and β3). Although CPα1 and CPα2 share \u3e90% sequence identity, the subunits contain a region of divergence that is highly conserved among the subunits. This suggests that the alpha isoforms have different functions and associate with different proteins. In a previous study, a yeast two-hybrid screen identified five proteins that interact with CPα1 and seven proteins that interact with CPα2. Utilizing bioinformatics, we confirmed the identity of the proteins; one novel protein was identified. To confirm the interactions of the candidate proteins with CPα1 or CPα2, we used a protein:protein technique, glutathione S-transferase, to pull down the putative binding proteins. Interactions were confirmed