The function of TSSK2 (testis specific serine kinase 2, Ensembl gene identifier ENSG00000206203) is as follows. Testis-specific serine/threonine-protein kinase required during spermatid development. Phosphorylates TSKS at 'Ser-288' and SPAG16. Involved in the late stages of spermatogenesis, during the reconstruction of the cytoplasm. During spermatogenesis, required for the transformation of a ring-shaped structure around the base of the flagellum originating from the chromatoid body. {ECO:0000269|PubMed:15044604, ECO:0000269|PubMed:18533145, ECO:0000269|PubMed:20729278}.