ferT encodes a meiosis-specific nuclear tyrosine kinase

ferT is a mouse testis-specific mRNA, shown previously to potentially encode a 51 kilodalton tyrosine kinase termed p51ferT. The accumulation of ferT RNA is restricted to primary spermatocytes that are at the prophase stage of the first spermatogenic meiotic division. By using antibodies raised against a synthetic peptide which was designed according to a putative p51ferT unique amino acid sequence, we have shown that testicular cells indeed contain a 51 kilodalton protein that is recognized by the anti-p51ferT antibodies. The protein was not detected in six nontesticular mouse tissues, nor was it detected, like the ferT RNA, in the testes of 14-day-old mice. These findings strongly suggest that the 51 kilodalton protein is p51ferT. Immunohistochemical staining localized p51ferT to meiotically dividing spermatocytes. Transfection experiments in CHO cells confirmed the nuclear localization of p51ferT in eukaryotic cells. p51ferT seems thus to be the first meiosis-specific nuclear tyrosine kinase described to date.