Zona-binding inhibitory factor-1 from human follicular fluid is an isoform of glycodelin.
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.
Chiu
P C N
PC
Department of Obstetrics and Gynaecology, University of Hong Kong, Queen Mary Hospital, Hong Kong, China.
Koistinen
R
R
Koistinen
H
H
Seppala
M
M
Lee
K F
KF
Yeung
W S B
WS
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
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