Enables magnesium ion binding activity; protein homodimerization activity; and protein serine/threonine kinase activity. Involved in several processes, including flagellated sperm motility; positive regulation of CREB transcription factor activity; and protein phosphorylation. Located in sperm flagellum. Orthologous to human TSSK4 (testis specific serine kinase 4). [provided by Alliance of Genome Resources, Apr 2022]