Abstract：In order to study the sequence characteristics of heat shock 70 kD protein-12B gene (HSPA12B) and its expression in yak (Bos grunniens) early in vitro fertilization (IVF) embryos, the specific primers were designed by the conservative sequence of HSPA12B gene of the cattle (Bos taurus)，and the gene sequence could be obtained by cloning. The HSPA12B sequence was analyzed by bioinformatics. The HSPA12B in early IVF embryos were detected by the methods of quantitative Real-time PCR (qRT-PCR). The results of bioinformatics showed the coding region of the yak HSPA12B gene was 705 bp in length, encoding 234 amino acids, and the content of Alanine resduces was the highest (about 10.3%) and the content of Asparagine resduces was the lowest (about 0.9%). According to homology analysis, the similarity of HSPA12B gene in yak and cattle was up to 99.5%, showing the HSPA12B gene was highly conserved. The protein was hydrophilic and had no signal peptide, which was not a transmembrane and secreted protein. qRT-PCR results showed that the HSPA12B in yak early embryos fertilized in vitro expressed in each period, and the relative expression of HSPA12B in 2-4 cell stage embryos was 14.814 8, 4.269 9 and 40.485 8 folds respectively, compared to the 5-8 cell stage embryos, morulae and blastocysts. The difference of the relative expression of HSPA12B between 2-4 cell stage embryos and 5-8 cell stage embryos，morula and blastocysts was very significant (P＜0.01). These results showed HSPA12B played an important role in the development of embryos IVF and can inhibit cell apoptosis, cell senescence, and regulate embryonic development.
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