Binds specifically and directly to substrates containing either a simple or bipartite NLS motif (PubMed:11311162). Promotes docking of import substrates to the nuclear envelope (PubMed:11311162). Seems to act as a cytosolic receptor for both simple and bipartite NLS motifs (PubMed:11311162). Necessary for correct nucleoporin localization within the germline (PubMed:11311162). Essential gene for embryonic and larval development (PubMed:11311162). May be dispensable for axon development, but required for axon regeneration in both mechanosensory and motor neurons (PubMed:31417366). Required for oogenic development, ima-1 and ima-2 cannot functionally compensate for loss of ima-3 (PubMed:11311162). Forms a complex with an importin beta subunit (PubMed:11311162). May interact with transcription factor cebp-1 (via N-terminus) (PubMed:31417366). Expressed in larval and adult germline and somatic tissues, including neurons. Expressed at high levels throughout all developmental stages. Larval lethality (PubMed:31417366). Mechanosensory neurons are born and develop normally (PubMed:31417366). However, cre-mediated knockdown targeted to mechanosensory neurons severely impairs axon regrowth of mechanosensory PLM neurons after injury (PubMed:31417366). Belongs to the importin alpha family.