A novel Xenopus laevis SRY-related gene, xSox33

The sex-determining region Y (SRY) gene and its related Sox genes encode transcriptional regulatory factors. In this study, we isolated and sequenced a novel Sox cDNA from African clawed frog (Xenopus laevis). The Sox gene was named xSox33. xSox33 was revealed to encode 244 amino acids. Reverse transcription-polymerase chain reaction (RT-PCR) showed that xSox33 was expressed at very low levels in some frog tissues including lung, ovary, skeletal muscle, testis, brain and heart. Its embryonic expression was also studied by RT-PCR. After the mid-blastula transition, the zygotic expression was initiated during gastrulation and the level was elevated as the embryogenesis proceeded. Electrophoretic mobility shift assay (EMSA) indicated that a recombinant xSox33 polypeptide was capable of binding to the nucleotide sequence AACAAT.