To provide an interpretation of X-ray and gamma-ray emission spectra of jets in Active Galactic
Nuclei (AGN) a detailed knowledge of particle acceleration at dissipation sites is required. In the
case of blazars, the dissipation of jet energy may involve mildly relativistic magnetized internal
shocks with Lorentz factor of γ ≤ 2. Of special interest for the emission modeling is the level of
kinetic energy exchange between protons and pre-heated electrons. While studies of ultrarelativis-
tic collisionless shocks demonstrate strong electron-ion coupling, mediated by the electron maser
instability in the shock precursor, the processes of shock formation, electromagnetic turbulence
production, and particle acceleration in the mildly relativistic regime are poorly known. Here we
present preliminary results of fully kinetic particle-in-cell simulation studies of mildly relativistic
superluminal shocks in strongly magnetized plasma. The main focus is on ion-to-electron energy
transfer processes and the effects of the electron-positron pair content.