title: Epitope topology and removal of mouse acrosomal plasma membrane by P12-targeted immunoaggregation.
abstract: P12 is a Kazal-type trypsin inhibitor that has been purified from mouse seminal vesicle secretion. We observed a slight impact of P12 on sperm capacitation, and demonstrated the removal of plasma membrane overlaying the acrosome region by immunoaggregation of P12 on mouse sperm. Further, we compared the immunoreactivity of P12 antibody to ten P12 variants, including six single-site mutated mutants (R19L, Y21V, D22G, R43G, K44S, and R45T), two multisite mutated mutants (R43G/K44S/R45T and L50H/R52G/K53A), and two deletion mutants (Nd10 and Cd8) in which 10 and 8 residues were deleted from the N- and C-terminals, respectively. We found that the N-terminal region, 43RKR45, and the C-terminal region, but not R19, Y21, and D22, are involved in the three epitopes that reside on one side and are three-dimensionally distant from R19, Y21, and D22 on the P12 molecule. Based on the epitope topology, we elucidated the structural basis by which P12 antibody immunoaggregated P12 on sperm head.
authors.affiliation: Institute of Bioscience and Biotechnology, National Taiwan Ocean University, Keelung, Taiwan.
authors.forename: Han-Jia
authors.initials: HJ
authors.lastname: Lin
authors.forename: Ching-Wei
authors.initials: CW
authors.lastname: Luo
authors.forename: Chia-Yih
authors.initials: CY
authors.lastname: Wang
authors.forename: Yee-Hsiung
authors.initials: YH
authors.lastname: Chen
mesh_terms: D000177:Acrosome / Q000378:metabolism*; D000595:Amino Acid Sequence; D000818:Animals; D002462:Cell Membrane / Q000378:metabolism*; D000939:Epitopes / Q000737:chemistry; D006023:Glycoproteins / Q000737:chemistry / Q000378:metabolism*; D008297:Male; D051379:Mice; D008958:Models, Molecular; D008969:Molecular Sequence Data; D029584:Prostatic Secretory Proteins / Q000737:chemistry / Q000378:metabolism*; D011480:Protease Inhibitors / Q000494:pharmacology; D017434:Protein Structure, Tertiary; D013075:Sperm Capacitation; D013094:Spermatozoa / Q000378:metabolism; D014359:Trypsin Inhibitor, Kazal Pancreatic
chemical_list: D000939:Epitopes; D006023:Glycoproteins; D029584:Prostatic Secretory Proteins; D011480:Protease Inhibitors; C487134:Spink1 protein, mouse; D014359:Trypsin Inhibitor, Kazal Pancreatic