An actuator for the actuation of at least one movable member of a motor vehicle transmission. The actuator includes a housing and a cover defining an internal volume in which are received at least one electric motor having a stator and a rotor mounted on a rotor shaft extending along an axis X1, a motor pinion fixed to the opposite end of the shaft from the rotor, a circuit board for supplying power to the stator and controlling the electric motor, and a reduction mechanism driven by the motor pinion. The housing or the cover includes an electrical connector which incorporates a semipermeable membrane allowing an exchange of gas between the inside of the actuator and the external surroundings.