title: Bull testicular haploid germ cells express a messenger encoding for a truncated form of the protein tyrosine kinase HCK.
abstract: Protein tyrosine phosphorylation is a process that has been studied worldwide during sperm capacitation and acrosomal exocytosis events. Although few capacitation-induced phosphotyrosine-containing proteins have been identified, little is known about the tyrosine kinases directly involved in this post-translational modification. Different studies from our and other groups using tyrosine kinase inhibitors suggest the involvement of members of the family of src-related tyrosine kinases in the sperm capacitation associated increase in protein tyrosine phosphorylation. Using a molecular biology approach, we report for the first time messengers encoding for members from the src-related tyrosine kinase family in bovine spermatogenic cells. Degenerated primers were designed within a highly homologous region specific to the family of src tyrosine kinases, and RNAs coding for c-src, c-yes, lyn, lck, and hck were identified in bull testis and haploid germ cells by RT-PCR. We also report the presence of a messenger in haploid bull germ cells that could encode for a truncated isoform of the hck tyrosine kinase. This messenger was detected by screening of a haploid germ cells cDNA library using the RT-PCR product homologous to hck as a probe. The presence of this transcript in haploid germ cell RNA preparations was validated by RT-PCR, 3'RACE, 5'RACE as well as Northern blot. Such a truncated protein could function as an adaptor protein or as a competitive inhibitor in spermiogenesis or mature sperm functions.
authors.affiliation: Département d'Obstétrique/Gynécologie, Centre de Recherche en Biologie de la Reproduction, Université Laval and Endocrinologie de la Reproduction, Centre de recherche du CHUQ, Québec, Canada.
authors.forename: Claudia
authors.initials: C
authors.lastname: Lalancette
authors.forename: Louis-Jean
authors.initials: LJ
authors.lastname: Bordeleau
authors.forename: Robert L
authors.initials: RL
authors.lastname: Faure
authors.forename: Pierre
authors.initials: P
authors.lastname: Leclerc
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000502:physiology; D000595:Amino Acid Sequence; D000727:Androgen-Binding Protein / Q000378:metabolism / Q000502:physiology; D000818:Animals; D001483:Base Sequence; D001667:Binding, Competitive / Q000235:genetics; D002417:Cattle; D015723:Gene Library; D006238:Haploidy; D007527:Isoenzymes / Q000096:biosynthesis / Q000235:genetics; D008297:Male; D008969:Molecular Sequence Data; D051572:Proto-Oncogene Proteins c-hck / Q000096:biosynthesis* / Q000235:genetics* / Q000378:metabolism; D012333:RNA, Messenger / Q000096:biosynthesis*; D013094:Spermatozoa / Q000201:enzymology*; D013737:Testis / Q000201:enzymology
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D000727:Androgen-Binding Protein; D007527:Isoenzymes; D012333:RNA, Messenger; D051572:Proto-Oncogene Proteins c-hck