Purified mouse egg zona pellucida glycoproteins polymerize into homomeric fibrils under non-denaturing conditions.
The mouse egg's zona pellucida (ZP) is composed of three glycoproteins, called ZP1, ZP2, and ZP3, that migrate as relatively broad, single bands on SDS-PAGE. The glycoproteins are organized within the ZP as a network of long interconnected fibrils that exhibit a structural periodicity. Here, ZP2 and ZP3 were purified by HPLC to homogeneity and analyzed by Blue Native- (BN-) PAGE and transmission electron microscopy (TEM), as well as by SDS-PAGE. As opposed to SDS-PAGE, BN-PAGE, and TEM permit analysis of ZP2 and ZP3 under non-denaturing conditions. ZP2 and ZP3 migrate on BN-PAGE, not as single bands, but as several discrete oligomers that give rise to larger structures which remain at the origin of the gel. Consistent with this, ZP2 and ZP3 are visualized by TEM as long interconnected fibrils that consist of contiguous beads. Therefore, under non-denaturing conditions both purified ZP2 and ZP3 polymerize into higher order structures. These findings are of interest since purified ZP3 inhibits binding of mouse sperm to eggs and induces sperm to undergo the acrosome reaction in vitro. Results presented here suggest that these biological effects of ZP3 are due to binding of homomeric fibrils of ZP3 to sperm.
Litscher
Eveline S
ES
Brookdale Department of Molecular, Cell and Developmental Biology, Mount Sinai School of Medicine, New York, New York 10029-6574, USA.
Janssen
William G
WG
Darie
Costel C
CC
Wassarman
Paul M
PM
D020106:Acrylamide / Q000494:pharmacology; D000818:Animals; D002851:Chromatography, High Pressure Liquid; D004305:Dose-Response Relationship, Drug; D004527:Egg Proteins / Q000032:analysis / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism* / Q000648:ultrastructure; D004591:Electrophoresis, Polyacrylamide Gel; D005260:Female; D005612:Freeze Drying; D008562:Membrane Glycoproteins / Q000032:analysis / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism* / Q000648:ultrastructure; D051379:Mice; D009865:Oocytes / Q000737:chemistry*; D011108:Polymers / Q000737:chemistry / Q000378:metabolism*; D017434:Protein Structure, Tertiary; D011956:Receptors, Cell Surface / Q000032:analysis / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism* / Q000648:ultrastructure; D016622:Silver Staining; D012967:Sodium Dodecyl Sulfate / Q000494:pharmacology; D012995:Solubility; D014508:Urea / Q000494:pharmacology; D000072216:Zona Pellucida Glycoproteins
D004527:Egg Proteins; D008562:Membrane Glycoproteins; D011108:Polymers; D011956:Receptors, Cell Surface; D000072216:Zona Pellucida Glycoproteins; C000606519:Zp1 protein, mouse; C000606520:Zp2 protein, mouse; C000606521:Zp3 protein, mouse; D020106:Acrylamide; D012967:Sodium Dodecyl Sulfate; D014508:Urea