Proteomic analysis of Tianzhu White Yak (Bos grunniens) testis at different sexual developmental stages.

To explore the protein expression profiles of white yak (Bos grunniens) testis at different sexual developmental stages. The protein profiles of yak testis were determined using two-dimensional electrophoresis and the expression levels of 298 protein spots were analyzed. Mass spectrometry was performed to identify those significantly differential expressed proteins; Western blotting was used to confirm the results. During the developmental stages, 29 protein spots showed more than twofold differences (p < 0.05) at ≥1 time point and were successfully identified. Two proteins were upregulated with age (category 1), five proteins (17.2%) were downregulated with age (category 2), four proteins were upregulated before 4 years of age and downregulated thereafter (category 3), fifteen proteins were upregulated before 2 years of age and downregulated thereafter (category 4), and three proteins fluctuated with age (category 5). The expression patterns of regucalcin and heat shock 60 kDa protein in category 2 were confirmed. The 29 differentially expressed proteins from yak testes (some had more than one function) were categorized into binding (n = 15), catalytic activity (n = 13), molecular function regulator (n = 4), antioxidant (n = 4), molecular transducer (n = 2), transporter (n = 1), and structural molecule (n = 1). The identification and analysis of these testis proteins may assist in understanding the developmental biology of reproduction system in male yak.