A novel member of the testis specific serine kinase family, tssk-3, expressed in the Leydig cells of sexually mature mice

We have recently characterized two members of a novel family of murine test is specific serine kinases, tssk-1 and tssk-2, expressed exclusively in spe rmatids undergoing spermiogenesis. Using a differential screening approach we have isolated a third family member, tssk-3. The open reading frame of t ssk-3 encodes a protein of 275 amino acids, consisting essentially of a ser ine/threonine protein kinase domain only. In contrast, tssk-1 and -2 have d istinct, approximately 100 amino acid domains located C-terminally to the k inase domain. Immunoprecipitation experiments revealed that while tssk-1 an d tssk-2 form detergent resistant complexes, tssk-3 is not associated with either protein. Expression of tssk-3 was induced at puberty, persisted duri ng adulthood and was restricted to the interstitial Leydig cells of post-pu bertal males. (C) 2000 Elsevier Science Ireland Ltd. All rights reserved.