title: Time-resolved sperm responses to an egg peptide measured by stopped-flow fluorometry.
abstract: Speract, a decapeptide from sea urchin egg jelly, induces various sperm responses. Stopped-flow fluorometry was used to examine the binding of labeled speract and the intracellular changes in pH (pH(i)) and Ca2+ ([Ca2+]i) it induces in sperm. We observed significant time delays for the increase in pH(i) and [Ca2+]i induced by 200 nM speract (69 and 190 ms, respectively). Also, we found that the receptor undergoes a pH(i)-dependent affinity change at around 129 ms. These time delays probably reflect biochemical processes underlying each sperm response to speract that circumscribe the time sequence of the signaling events.
authors.affiliation: Departamento de Genética y Fisiología Molecular, Universidad Nacional Autónoma de México, Cuernavaca, Morelos, 62250, México.
authors.forename: T
authors.initials: T
authors.lastname: Nishigaki
authors.forename: F Z
authors.initials: FZ
authors.lastname: Zamudio
authors.forename: L D
authors.initials: LD
authors.lastname: Possani
authors.forename: A
authors.initials: A
authors.lastname: Darszon
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism; D002633:Chemotaxis / Q000187:drug effects; D005456:Fluorescent Dyes / Q000737:chemistry; D005470:Fluorometry / Q000379:methods; D006863:Hydrogen-Ion Concentration / Q000187:drug effects; D007424:Intracellular Fluid / Q000378:metabolism; D008297:Male; D009842:Oligopeptides / Q000737:chemistry / Q000494:pharmacology*; D011485:Protein Binding / Q000502:physiology; D011930:Reaction Time / Q000187:drug effects; D011956:Receptors, Cell Surface / Q000378:metabolism; D012617:Sea Urchins; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology; D013094:Spermatozoa / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism*
chemical_list: D005456:Fluorescent Dyes; D009842:Oligopeptides; D011956:Receptors, Cell Surface; C035027:egg surface sperm receptor; C028364:speract; D002118:Calcium