The conductivity of a two-dimensional electron gas in an inverted heterostructure containing InAs self-assembled quantum dots (SAQD’s) in the vicinity of the electron gas is studied as a function of density and temperature. Field electrodes are employed to control the density in the electron gas and the electron occupation state of the SAQD’s independently. Furthermore, the disorder arising from ionized impurities is tuned via illumination of the cold sample with subband gap radiation. The electron mobility is found to increase with increasing SAQD’s occupation if the disorder is larger than the inhomogeneity of the SAQD’s energy-levels distribution.