title: Zona-binding inhibitory factor-1 from human follicular fluid is an isoform of glycodelin.
abstract: Zona-binding inhibitory factor-1 (ZIF-1), a glycoprotein in human follicular fluid, reduces the binding of spermatozoa to the zona pellucida. ZIF-1 has a number of properties similar to those of glycodelin-A from human follicular fluid. The objective of this study was to compare the biochemical characteristics of these two glycoproteins. N-terminal sequencing and protease-digested peptide mapping showed that ZIF-1 and glycodelin-A have the same protein core. However, these glycoproteins differ in their oligosaccharide chains, as demonstrated by fluorophore-assisted carbohydrate electrophoresis, lectin-binding ability, and isoelectric focusing. ZIF-1 inhibited spermatozoa-zona pellucida binding slightly more than did glycodelin-A and significantly suppressed progesterone-induced acrosome reaction of human spermatozoa. Indirect immunofluorescence staining revealed specific binding of glycodelin-A and ZIF-1 to the acrosome region of human spermatozoa, where ZIF-1 produced a stronger signal than did glycodelin-A at the same protein concentration. These data suggest that ZIF-1 is a differentially glycosylated isoform of glycodelin that potently inhibits human sperm-egg interaction. Future study on the function role of ZIF-1 would provide a better understanding of the regulation of fertilization in humans.
authors.affiliation: Department of Obstetrics and Gynaecology, University of Hong Kong, Queen Mary Hospital, Hong Kong, China.
authors.forename: P C N
authors.initials: PC
authors.lastname: Chiu
authors.forename: R
authors.initials: R
authors.lastname: Koistinen
authors.forename: H
authors.initials: H
authors.lastname: Koistinen
authors.forename: M
authors.initials: M
authors.lastname: Seppala
authors.forename: K F
authors.initials: KF
authors.lastname: Lee
authors.forename: W S B
authors.initials: WS
authors.lastname: Yeung
mesh_terms: D000595:Amino Acid Sequence; D004527:Egg Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D005260:Female; D015571:Follicular Fluid / Q000378:metabolism*; D000071816:Glycodelin; D006023:Glycoproteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D066298:In Vitro Techniques; D008297:Male; D008562:Membrane Glycoproteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D009844:Oligosaccharides / Q000737:chemistry; D011257:Pregnancy Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D020033:Protein Isoforms / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D011956:Receptors, Cell Surface; D013084:Sperm-Ovum Interactions / Q000502:physiology; D015044:Zona Pellucida / Q000378:metabolism; D000072216:Zona Pellucida Glycoproteins
chemical_list: D004527:Egg Proteins; D000071816:Glycodelin; D006023:Glycoproteins; D008562:Membrane Glycoproteins; D009844:Oligosaccharides; C045246:PAEP protein, human; D011257:Pregnancy Proteins; D020033:Protein Isoforms; D011956:Receptors, Cell Surface; D000072216:Zona Pellucida Glycoproteins