Towards delineation of a developmental α-importome in the mammalian male germline

► This is the first study to reveal the α-importome in mammalian spermatogenesis. ► Highly purified rat male germ cells were used for an unbiased proteomic approach. ► A total of 22 proteins were identified unequivocally. ► The cNLS Mapper was validated for identifying importin α binding motifs. ► The identified SMC6 NLS confers nuclear transport, generally via importin α/β1