Fig. 2. Binding of -PKC to cardiac myofilaments. (A) Western blot of myofilament pellets showing binding of purified -PKC in absence or presence of 50 µM arachidonic acid (AA). -PKC concentrations (in µM): lane 1, 0; lane 2, 0.1; lane 3, 0.2; lane 4, 0.5; lane 5, 1. (B) Summary of -PKC binding to myofilaments. The solid circles (in the presence of AA) represents a fit to B/B_max=[-PKC]/([-PKC] + EC₅₀), with EC₅₀=86 nM and B_max=15 pmol (or 75 pmol/mg protein). The stoichiometry of binding was 15 pmols -PKC bound per 2 nmoles actin monomers or a 1/130 ratio. The open circles represent a linear regression of -PKC binding in the absence of AA.