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dc.contributor.authorYu, Yangen
dc.date2008-11-27 15:33:50.226
dc.date.accessioned2008-11-27T22:40:11Z
dc.date.available2008-11-27T22:40:11Z
dc.date.issued2008-11-27T22:40:11Z
dc.identifier.urihttp://hdl.handle.net/1974/1589
dc.descriptionThesis (Ph.D, Anatomy & Cell Biology) -- Queen's University, 2008-11-27 15:33:50.226en
dc.description.abstractDuring mammalian fertilization, the exposure of the inner acrosomal membrane (IAM) after acrosomal exocytosis is essential for the secondary binding between sperm and zona pellucida (ZP) of the oocyte, a prerequisite for sperm penetration through the ZP. The identification of the sperm protein(s) responsible for secondary binding has posed a challenge for researchers. We were able to isolate a sperm head fraction in which the IAM was exposed. Attached to the IAM was an electon dense layer, which we termed the IAM extracellular coat (IAMC). The IAMC was also observable in acrosome reacted sperm. High salt extraction removed the IAMC including a prominent 38 kDa polypeptide, referred to as IAM38. Antibodies raised against IAM38 confirmed its presence in the IAMC of intact, sonicated, and acrosome-reacted sperm. Sequencing of IAM38 revealed it as the ortholog of porcine SP38, a protein that was found to bind specifically to ZP2 but whose intra-acrosomal location was not known. We showed that IAM38 occupied the leading edge of sperm contact with the zona pellucida during fertilization, and that secondary binding and fertilization were inhibited in vitro by antibodies directed against IAM38. As for the mechanism of secondary sperm-zona binding by IAM38, we provided evidence that the synthetic peptide derived from the ZP2-binding motif of IAM38 had a competitive inhibitory effect on both sperm-zona binding and fertilization while its mutant form was ineffective. In summary, our study provides a novel approach to obtain direct information on the peripheral and integral protein composition of the IAM and consolidates IAM38 as a genuine secondary sperm-zona binding protein. In addition, our investigation also provides an ultrastructural description of the origin, expression and assembly of IAM38 during spermatogenesis. It shows that IAM38 is originally secreted by the Golgi apparatus as part of the dense contents of the proacrosomic granules but later, during acrosome capping phase of spermiogenesis, is redistributed to the inner periphery of the acrosomal membrane. This relocation occurs at the time of acrosomal compaction, an obligatory structural change that fails to occur in Zpbp1-/- knockout mice, which do not express IAM38 and are infertile.en
dc.format.extent6726750 bytes
dc.format.mimetypeapplication/pdf
dc.language.isoengen
dc.relation.ispartofseriesCanadian thesesen
dc.rightsThis publication is made available by the authority of the copyright owner solely for the purpose of private study and research and may not be copied or reproduced except as permitted by the copyright laws without written authority from the copyright owner.en
dc.subjectSpermiogenesisen
dc.subjectSpermen
dc.subjectAcrosomeen
dc.subjectAcrosomal Biogenesisen
dc.subjectInner Acrosomal Membrane (IAM)en
dc.subjectInner Acrosomal Membrane Coat (IAMC)en
dc.subjectIAM38en
dc.subjectZona Pellucidaen
dc.subjectSperm-Zona Secondary Bindingen
dc.subjectZona Penetrationen
dc.subjectFertilizationen
dc.titleThe Identification and Characterization of an Inner Acrosomal Membrane Associated Protein, IAM38, Responsible for Secondary Sperm-Zona Binding During Fertilizationen
dc.typethesisen
dc.description.degreePhDen
dc.contributor.supervisorOko, Richarden
dc.contributor.departmentAnatomy and Cell Biologyen
dc.degree.grantorQueen's University at Kingstonen


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