Identification and Localization of a Ligand Molecule of Xenopus Cortical Granule Lectins

概要

論文の詳細を見る
This study aimed to identify the ligand molecule of the cortical granule lectins which participate in the formation of the fertilization (F) layer in Xenopus laevis. Comparison of fertilization envelopes (FEs) with and without the F layer by SDS-PAGE showed a 105-kDa glycoprotein (gp105) only in the former FEs. This glycoprotein was isolated by differential centrifugation and electrophoretical extraction from an F layer extract. Immunoblotting with an antiserum against gp 105 produced staining on the gp 105 in the FEs ; the relative amount of gp 105 increased during the hatching period due to the digestion of vitelline envelope components. Staining on westernblots with HRP-conjugated peanut agglutinin suggested that gp 105 contains a small amount of galactosides. With immunoelectron microscopy, gold particles indicating the location of gp 105 were visible on the pre-fertilization (PF) layer of eggs obtained from the pars recta 2 (PR2) and the uterus of the oviduct, but they were few on the F layer of activated eggs. With the PA-CrA-Silver method for detecting carbohydrates, silver particles appeared on the PF layer but not on the main body of the F layer. The binding of gold-conjugated lectins to gp 105 on westernblots showed that gp 105 interacts with the cortical granule lectins. It was concluded from these results that gp 105 is a natural ligand of the lectins, and that it resides in the PF layer and is supplied to eggs at the PR2.
1994-04-15