The aspartyl protease mediates proteolytic cleavages of Gag and Gag-Pol polyproteins during or shortly after the release of the virion from the plasma membrane. Cleavages take place as an ordered, step-wise cascade to yield mature proteins. This process is called maturation. Displays maximal activity during the budding process just prior to particle release from the cell. Intracisternal A particles (IAPs) are defective retroviral elements. Due to extensive mutations in the envelope coding sequence, IAPs can only form defective viral particles confined to the intracisternae of the Golgi. IAPs are an important class of transposable elements that induce genomic mutations and cell transformation by disrupting gene expression.