NUCLEAR-LOCALIZATION OF THE TESTIS-DETERMINING GENE-PRODUCT SRY

We have studied the expression of the human SRY protein (termed p27SRY ) in two different cell lines by using specific antibodies. Confocal m icroscopy enabled us to localize p27SRY precisely in the nucleus in a discrete punctuate pattern. Furthermore, through microinjection experi ments, we have demonstrated that the localization of the p27SRY protei n into the nucleus was an event involving the NH2-terminal part of the high mobility group (HMG) domain. With the help of several synthetic peptides and various p27SRY mutants, we have characterized a bipartite basic motif in this part of the protein corresponding to a nuclear lo calization signal. This nuclear localization signal appears to be high ly conserved in SRY box- and HMB box-containing proteins, suggesting c ommon properties of nuclear targeting within the HMG box protein famil y.