Bovine zone pellucida (ZP) glycoproteins from ovarian egg emerged as three bands with molecular mass of 78 kDa, 64 kDa and 21 kDa in SDS-PAGE under reducing conditions. Endo-beta-galactosidase (EbetaG) digestion of the glycoproteins yielded five products with molecular mass of 76 kDa (EbetaG-76), 68 kDa (EbetaG-68), 63 kDa (EbetaG-63), 47 kDa (EbetaG-47) and 21 kDa (EbetaG-21) under the same conditions. The N-terminal amino acid sequences of EbetaG-76 and EbetaG-21 were identical. This fact together with the results of diagonal SDS-PAGE indicated that EbetaG-21 (N-terminal region) is linked to EbetaG-63 (C-terminal region) through disulfide bond to form EbetaG-76. Immunoblot analysis using anti-pig ZP protein antibodies revealed that bovine EbetaG-76, EbetaG-68 and EbetaG-47 correspond to pig PZP2, PZP3 alpha and PZP3 beta glycoproteins, respectively. The EbetaG-76 and EbetaG-68 components were shown to be specifically cleaved during fertilization.