Binds specifically and directly to substrates containing either a simple or bipartite NLS motif. Promotes docking of import substrates to the nuclear envelope. Seems to act as a cytosolic receptor for both simple and bipartite NLS motifs (By similarity). Forms a complex with an importin beta subunit. Adult germline tissues. Expressed very weakly in early larvae, levels of expression increase in L4 and adult stages when germ cells are continually proliferating. Does not contain ARM repeats, but instead Ser charged repeats. May have specificity for cargos distinct from that of other importin alpha subunits. Belongs to the importin alpha family.