Mouse Zfx protein is similar to Zfy-2: each contains an acidic activating domain and 13 zinc fingers.

The Zfy gene is located on the Y chromosome of placental mammals and encodes a zinc finger protein which may serve as the primary sex-determining signal. A related gene, Zfx, is similarly conserved on the X chromosome. Unlike that in most mammals, the mouse genome contains four homologous zinc finger loci: Zfy-1, Zfy-2, Zfx, and Zfa (on an autosome). We report that, in contrast to the mouse Zfy genes, Zfx is widely transcribed in embryos, newborns, and adults, both male and female. Moreover, Zfx transcripts contain long 3' untranslated sequences which are phylogenetically conserved. Zfa is a processed gene derived from Zfx. An analysis of cDNA clones demonstrated that Zfx encodes a 799-amino-acid protein that is 70% identical to the mouse Zfy-1 and Zfy-2 proteins. Zfx, Zfy-1, and Zfy-2 contain highly acidic amino-terminal domains and carboxy-terminal regions containing 13 zinc fingers. When fused to the DNA-binding domain of GAL4, the acidic domains of Zfx and Zfy-2 activated transcription in yeast cells.