While the main function of Smoks is to control sperm motility, the role of Smok-Tcr, with reduced kinase activity, is to counterbalance a signaling impairment caused by the distorter/sterility loci, giving t-sperm an advantage in reaching the oocytes. Transmission ratio distortion also called segregation distortion is the name given to the phenomenon above-mentioned. Being associated with the T-complex, it allows males heterozygous for a complete t-haplotype to preferentially transmit the t-haplotype chromosome. ATP + L-seryl-[protein] = ADP + H(+) + O-phospho-L-seryl-[protein] ATP + L-threonyl-[protein] = ADP + H(+) + O-phospho-L-threonyl-[protein] Testis-specific. Expressed in the testis from 22 days postpartum (22 dpp). Expressed late in spermiogenesis, only in Tcr-containing t-haplotypes. Encoded on the T-complex, a region of 20-30 Mb on proximal third of mouse chromosome 17. Naturally occurring variant forms of the T-complex, known as complete t-haplotypes, are found in wild mouse populations. The t-haplotypes contain at least four nonoverlapping inversions that suppress recombination with the wild-type chromosome, and lock into strong linkage disequilibrium loci affecting normal transmission of the chromosome, male gametogenesis and embryonic development. T6 allele. Belongs to the protein kinase superfamily. Tyr protein kinase family. Smok subfamily. Although it is derived from a rearrangement with the neighboring RSK3 gene, it plays a crucial role in t-haplotype cells.