In order to identify novel genes involved in spermatogenesis, testis cDNA samples from Balb/C mice of different postnatal days were hybridized with the whole mouse genome Affymetrix chip to screen the testis-specific genes. The characteristics of the selected genes were analyzed by RT-PCR as well as other bioinformatic tools. A novel differentially expressed testis-specific gene (GenBank Accession No: NM_029042) in the developmental stages of testes was identified, and named TSCPA. Cellular mapping prediction of TSCPA indicated that its protein was probably expressed in nuclei, and one putative domain (aa 332 377) was anchoring domain of cAMP-dependent type Ⅱ PK. The result of subcellular localization of GFP-TSCPA fusion protein in Cos-7 cells showed that TSCPA protein was expressed in nuclei. RT-PCR analysis revealed that TSCPA was expressed specifically in mouse and human testis. TSCPA gene was expressed weakly in 21-day-old mouse testis and the expression was increased gradually from 38th day to 6th month of mouse testes. No expression of hTSCPA was found in cryptorchidism and Sertoli-cell-only syndrome patients. It was concluded that the expression profile of TSCPA in human and mice indicated that TSCPA might play an important role in spermatogenesis.