Involved in the transport of the viral pre-integration (PIC) complex to the nucleus during the early stages of the infection. This function is crucial for viral infection of non-dividing macrophages. May interact with karyopherin alpha/KPNA1 and KPNA2 to increase their affinity for proteins containing basic-type nuclear localization signal, including the viral matrix protein MA, thus facilitating the translocation of the viral genome into the nucleus. May also act directly at the nuclear pore complex, by binding nucleoporins phenylalanine-glycine (FG)-repeat regions (By similarity).