TSSK2 is a testis-specific serine/threonine-protein kinase required during spermatid development. This protein phosphorylates TSKS at 'Ser-288' and SPAG16. TSSK2 involved in the late stages of spermatogenesis, during the reconstruction of the cytoplasm. During spermatogenesis, it is required for the transformation of a ring-shaped structure around the base of the flagellum originating from the chromatoid body. Recombinant human TSSK2 protein, fused to His-tag at N-terminus, was expressed in E.coli.