Three-dimensional structure of the zona pellucida

Abstract

The zona pellucida is the spherical glycoprotein shell that surrounds the mammalian oocyte at fertilization. Penetration of this shell by spermatozoa plays a crucial role in mammalian fertilization and any inability of spermatozoa to penetrate the zona pellucida inevitably leads to infertility. The purpose of this review is to summarize what we know or can infer about the three-dimensional structure of the zona pellucida, its construction and its properties as a polymer. Because the focus of the review is on three-dimensional structure, it relies heavily on data from mice. Features of the zona pellucida are discussed and two models for its construction are considered. The cortical reaction and its possible effects are discussed and avenues for future experimental work are identified.

Sperm arylsulfatase A binds to mZP2 and mZP3 glycoproteins in a nonenzymatic manner

“…Nonreducing SDS-PAGE/silver staining of solubilized mZP glycoproteins revealed the highest abundance of mZP2 followed by mZP3 and mZP1 ( Fig. 2A, left lane) in agreement with the previous report (Green 1997). Size exclusion HPLC on a Bio-Sil SEC 250 column separated solubilized mouse ZP glycoproteins into three peaks with retention times of 57.3, 62.2, and 66.8 min (Fig.…”

“…The yield of mZP1, mZP2, and mZP3 was about 35, 200, and 150 ng/ovary, respectively. The weight ratio of the purified mZP2 to mZP3 (1:0.75) was similar to that previously described (1:0.7) (Green 1997), although the ratio of the obtained mZP1 to that of mZP2 (0.18:1) was lower than the described value (0.3:1). Subsequently, mZP2 and mZP3 were also purified by electroelution from the polyacrylamide gel of total solubilized ZP glycoproteins that were subjected to SDS-PAGE.…”

“…In the first set of experiments, the proportion of the three mZP glycoproteins used for this immobilization mimicked that present in the total solubilized ZP (i.e. 0.3 mg for mZP1, 1 mg for mZP2, and 0.7 mg for mZP3 ;Green 1997). At this weight ratio of the three mZP glycoproteins, ASA bound to mZP2 at the highest level, followed by mZP3, whereas the binding of ASA to mZP1 was at a background level as observed with ovalbumin (Fig.…”

“…(A) One microgram of fetuin, ovalbumin, and solubilized whole mZP glycoproteins, 0.3 mg of mZP1, 1 mg of mZP2, and 0.7 mg of mZP3 were dotted onto nitrocellulose membrane. The weight ratio of mZP1, mZP2, and mZP3 used for the dotting was as described previously (Green 1997). After incubation with purified ASA (3 mg), the membrane was washed extensively to remove unbound protein and probed for the ASA binding by anti-ASA antibody and HRP-conjugated secondary antibody.…”

Singular features of fertilization and their impact on the male reproductive system in eutherian mammals

“…Approximately an order of magnitude thicker than that in most of the invertebrates and vertebrates, including some marsupials, its three or four constituent glycoproteins, first probed by Paul Wassarman and colleagues are linked to a degree by -S-S-bonds. Moreover, not only does it display an elastic rigidity (Green 1997), but it also proves to be relatively insensitive to proteases. We have observed that the marsupial zona disappears in some 2-8 s on exposure to 1.0-0.5% trypsin at pH 7.2, whereas that of most eutherians shows no visible change for 2 min or more.…”