title: Role of tyrosine phosphorylation of flagellar proteins in hamster sperm hyperactivation.
abstract: Despite extensive study of sperm motility, little is known of the mechanism of mammalian sperm hyperactivation. Here we describe a novel method for preparation of rodent sperm flagella and use it to show a correlation between tyrosine phosphorylation of flagellar proteins and hyperactivation of hamster sperm. When hyperactivation was produced by a 3.5-h incubation in a medium supporting capacitation, four major tyrosine-phosphorylated peptides of 90-, 80-, 62-, and 48-kDa mass were detected in flagellar extracts. Incubation with calyculin A, an inhibitor of protein phosphatases 1 and 2A, produced hyperactivation within 40 min but only a single 80-kDa phosphotyrosine-containing flagellar component. Conversely, incubation with inhibitors of either protein kinase A (H8) or protein tyrosine kinase (tyrphostin 47) prevented both hyperactivation and the production of tyrosine-phosphorylated flagellar peptides. These results indicate a strong correlation of hyperactivation with the tyrosine phosphorylation of sperm flagellar peptides, and they strongly implicate an 80-kDa component as a major mediator of the mechanism that produces hyperactivated motility of hamster sperm.
authors.affiliation: Department of Biology, College of Arts and Sciences, The University of Tokyo, Komaba, Meguro-ku, Tokyo 153, Japan. ysi@nimbus.temple.edu
authors.forename: Y
authors.initials: Y
authors.lastname: Si
authors.forename: M
authors.initials: M
authors.lastname: Okuno
mesh_terms: D000818:Animals; D003994:Bucladesine / Q000494:pharmacology; D006224:Cricetinae; D003470:Culture Media; D017868:Cyclic AMP-Dependent Protein Kinases / Q000037:antagonists & inhibitors; D004791:Enzyme Inhibitors / Q000494:pharmacology; D007700:Kinetics; D008297:Male; D008387:Marine Toxins; D008647:Mesocricetus; D019319:Okadaic Acid / Q000494:pharmacology; D010080:Oxazoles / Q000494:pharmacology; D010749:Phosphoprotein Phosphatases / Q000037:antagonists & inhibitors; D010750:Phosphoproteins / Q000032:analysis; D010766:Phosphorylation; D019000:Phosphotyrosine / Q000378:metabolism*; D011505:Protein-Tyrosine Kinases / Q000037:antagonists & inhibitors; D011506:Proteins / Q000378:metabolism*; D013075:Sperm Capacitation; D013082:Sperm Tail / Q000737:chemistry*; D013094:Spermatozoa / Q000187:drug effects / Q000502:physiology*
chemical_list: D003470:Culture Media; D004791:Enzyme Inhibitors; D008387:Marine Toxins; D010080:Oxazoles; D010750:Phosphoproteins; D011506:Proteins; D019319:Okadaic Acid; D019000:Phosphotyrosine; D003994:Bucladesine; C059041:calyculin A; D011505:Protein-Tyrosine Kinases; D017868:Cyclic AMP-Dependent Protein Kinases; D010749:Phosphoprotein Phosphatases