TSKS may play a role in testicular physiology, spermatogenesis or spermiogenesis. Expression of the encoded protein is highest in the testis and down-regulated in testicular cancer. The gene is localized to the region 19q13.3 among the related RAS viral oncogene homolog (RRAS) and interferon regulatory factor 3 (IRF3) genes, which are both involved in tumorigenesis pathways and progression. The deduced 592-amino acid protein has a calculated molecular mass of 65.1 kD. TSKS has an N-terminal signal peptide and several potential phosphorylation and glycosylation sites, but no transmembrane region. It shares 73% amino acid identity with mouse Tsks. RT-PCR detected highest expression in testis, with much lower expression in prostate, placenta, fetal liver, thymus, and mammary gland.