Dynamic subcellular distribution of the DAZL protein is confined to primate male germ cells

We have examined the location of the DAZL protein in fetal and adult rodent s and human specimens and found that there is a shift from a predominantly nuclear to a predominantly cytoplasmic distribution of the protein in human testis, In rat testis and human ovary, however, the protein is predominant ly, if not exclusively, cytoplasmic throughout germ cell development. One p ossible explanation for this could be that the DAZ protein is responsible f or the nuclear localization of DAZL in human males. We have tested this hyp othesis by examining the testis of marmosets, which lack the Daz genes and have found that the DAZL protein is both nuclear and cytoplasmic in spermat ogonia, and by analyzing testis sections from DAZ-defeted patients in whom the cytoplasmic location of DAZL is evident in remaining germ cells. Transf ection experiments indicate that the differences in DAZL expression between rodents and humans are not caused by the amino acid differences between th e 2 proteins, and that DAZL is a cytoplasmic protein per se. Variations in location seem to be independent of the presence of the DAZ protein are spec ies specific and. as in Drosophila, may not have great functional significa nce.