title: Remodeling of the plasma membrane in preparation for sperm-egg recognition: roles of acrosomal proteins.
abstract: The interaction of sperm with the egg's extracellular matrix, the zona pellucida (ZP) is the first step of the union between male and female gametes. The molecular mechanisms of this process have been studied for the past six decades with the results obtained being both interesting and confusing. In this article, we describe our recent work, which attempts to address two lines of questions from previous studies. First, because there are numerous ZP binding proteins reported by various researchers, how do these proteins act together in sperm-ZP interaction? Second, why do a number of acrosomal proteins have ZP affinity? Are they involved mainly in the initial sperm-ZP binding or rather in anchoring acrosome reacting/reacted spermatozoa to the ZP? Our studies reveal that a number of ZP binding proteins and chaperones, extracted from the anterior sperm head plasma membrane, coexist as high molecular weight (HMW) complexes, and that these complexes in capacitated spermatozoa have preferential ability to bind to the ZP. Zonadhesin (ZAN), known as an acrosomal protein with ZP affinity, is one of these proteins in the HMW complexes. Immunoprecipitation indicates that ZAN interacts with other acrosomal proteins, proacrosin/acrosin and sp32 (ACRBP), also present in the HMW complexes. Immunodetection of ZAN and proacrosin/acrosin on spermatozoa further indicates that both proteins traffic to the sperm head surface during capacitation where the sperm acrosomal matrix is still intact, and therefore they are likely involved in the initial sperm-ZP binding step.
authors.affiliation: Chronic Disease Program, Ottawa Hospital Research Institute, Ottawa; Department of Obstetrics and Gynaecology, University of Ottawa; Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ontario, Canada, .
authors.forename: Nongnuj
authors.initials: N
authors.lastname: Tanphaichitr
authors.forename: Kessiri
authors.initials: K
authors.lastname: Kongmanas
authors.forename: Hathairat
authors.initials: H
authors.lastname: Kruevaisayawan
authors.forename: Arpornrad
authors.initials: A
authors.lastname: Saewu
authors.forename: Clarissa
authors.initials: C
authors.lastname: Sugeng
authors.forename: Jason
authors.initials: J
authors.lastname: Fernandes
authors.forename: Puneet
authors.initials: P
authors.lastname: Souda
authors.forename: Jonathan B
authors.initials: JB
authors.lastname: Angel
authors.forename: Kym F
authors.initials: KF
authors.lastname: Faull
authors.forename: R John
authors.initials: RJ
authors.lastname: Aitken
authors.forename: Julian
authors.initials: J
authors.lastname: Whitelegge
authors.forename: Daniel
authors.initials: D
authors.lastname: Hardy
authors.forename: Trish
authors.initials: T
authors.lastname: Berger
authors.forename: Mark
authors.initials: M
authors.lastname: Baker
mesh_terms: D000177:Acrosome / Q000502:physiology* / Q000648:ultrastructure; D002462:Cell Membrane / Q000648:ultrastructure*; D005260:Female; D006801:Humans; D008297:Male; D010063:Ovum / Q000502:physiology* / Q000648:ultrastructure; D013075:Sperm Capacitation / Q000502:physiology; D013084:Sperm-Ovum Interactions / Q000502:physiology*; D013094:Spermatozoa / Q000502:physiology* / Q000648:ultrastructure; D015044:Zona Pellucida / Q000502:physiology