Identification of Proteins Interacting with Actin Capping Protein Alpha Isoforms in Heart Muscle of Mice

Actin, an essential component of all living cells, contributes to cell shape, cell motility and the integrity of specific structures such as the sarcomere of striated muscle. Actin molecules are rod like in structure, and are composed of many identical pieces that attach and disassociate in a dynamic process. Capping protein (CP) anchors actin filaments, regulates the length of actin molecules, and maintains a cell\u27s ability to contract and relax. CP is a heterodimer composed of an alpha and beta subunit. There are three forms of the alpha subunit (αl, α2, and α3) and three forms of the beta subunit (β1, β2, and β3). Previous studies indicate that β1 and β2 have unique localizations and functions within murine myocardium. Recent studies have shown that α1 and α2 co-localize in myocardium but have distinct localizations in skeletal muscle cells. This early evidence suggests that αl and α2 may also have novel functions within muscle cells and may interact with novel proteins. The goal of this research is to identify cellular proteins that interact with α1 and α2 utilizing coimmunoprecipitation. This was accomplished using previously generated polyclonal rabbit anti-αl and chicken anti-α2 antibodies. The antibodies were purified and chemically attached to an immobilized matrix. The matrix is currently being used to identify novel proteins that interact with αl and α2. The results will be analyzed by Sodium Dodecyl Sulfate Polyacrylamide Gel Electrophoresis, native gel electrophoresis and Western blot analysis