In this work, we use molecular dynamics and lattice-Boltzmann simulations to study the properties of charged Janus particles in an electric field. We show that for a relatively small net charge and a thick electrostatic diffuse layer, mobilities of Janus particles and uniformly charged colloids of the same net charge are identical. However, for higher charges and thinner diffuse layers, the Janus particles always show lower electrophoretic mobility. We also demonstrate that the Janus particles align with the electric field and the angular deviation from the field's direction is related to their dipole moment. We show that the latter is affected by the thickness of electrostatic diffuse layer and strongly correlates with the electrophoretic mobility.