This paper proposes a memory proportionate affine projection sign algorithm (IAF-MP-APSA) by assigning an individual activation factor to each filter coefficient. In this algorithm, each individual activation factor is calculated by past and current values of the corresponding coefficient magnitude. Moreover, taking into account the memory property of the proportionate factors leads to a decrease in computational complexity. Simulation results to estimate impulse responses having high sparseness have demonstrated that the IAF-MP-APSA not only inherits good robustness of the affine projection sign algorithm (APSA) against impulsive noise, but also outperforms other existing proportionate APSAs in terms of convergence rate and tracking capability.