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.