Glycodelin-A interacts with fucosyltransferase on human sperm plasma membrane to inhibit spermatozoa-zona pellucida binding.
Fertilization depends on successful binding of the spermatozoa to the zona pellucida of the oocyte. Glycodelin-A inhibits spermatozoa-zona pellucida binding. Previous data showed that glycodelin-A receptor(s) and zona pellucida protein receptor(s) on human spermatozoa are closely related. Using a chemical cross-linking approach, the glycodelin-A-sperm receptor complex was isolated. The receptor was identified to be fucosyltransferase-5 (FUT5) by mass spectrometry and confirmed with the use of anti-FUT5 antibodies. Sperm FUT5 was an externally oriented integral membrane protein in the acrosomal region of human spermatozoa. Biologically active FUT5 was purified from spermatozoa. Co-immunoprecipitation confirmed the interaction between glycodelin-A and sperm FUT5. Solubilized zona pellucida reduced the binding of glycodelin-A to sperm FUT5. An anti-FUT5 antibody and FUT5 acceptor blocked the binding of glycodelin-A to spermatozoa and the zona binding inhibitory activity of glycodelin-A. Sperm FUT5 bound strongly to intact and solubilized human zona pellucida. The equilibrium dissociation constant of sperm FUT5 binding to solubilized zona pellucida was 42.82 pmol/ml. These observations suggest that human sperm FUT5 is a receptor of glycodelin-A and zona pellucida proteins, and that glycodelin-A inhibits spermatozoa-zona binding by blocking the binding of sperm FUT5 to the zona pellucida.
Chiu
Philip C N
PC
Department of Obstetrics and Gynaecology, University of Hong Kong, Queen Mary Hospital, Pokfulam Road, Hong Kong, China.
Chung
Man-Kin
MK
Koistinen
Riitta
R
Koistinen
Hannu
H
Seppala
Markku
M
Ho
Pak-Chung
PC
Ng
Ernest H Y
EH
Lee
Kai-Fai
KF
Yeung
William S B
WS
D000906:Antibodies / Q000494:pharmacology; D002462:Cell Membrane / Q000201:enzymology; D005260:Female; D005647:Fucosyltransferases / Q000276:immunology / Q000302:isolation & purification / Q000378:metabolism*; D000071816:Glycodelin; D006023:Glycoproteins / Q000302:isolation & purification / Q000378:metabolism*; D006801:Humans; D047468:Immunoprecipitation; D008297:Male; D011257:Pregnancy Proteins / Q000302:isolation & purification / Q000378:metabolism*; D011485:Protein Binding / Q000502:physiology; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D013084:Sperm-Ovum Interactions / Q000502:physiology*; D013094:Spermatozoa / Q000201:enzymology*; D015044:Zona Pellucida / Q000502:physiology*
D000906:Antibodies; D000071816:Glycodelin; D006023:Glycoproteins; C045246:PAEP protein, human; D011257:Pregnancy Proteins; D005647:Fucosyltransferases; C435083:fucosyltransferase V