Mechanisms of G6PD isozyme pattern changes at fertilization

✍ Scribed by Barber, Mary Lee ;Kolan, David M. ;Yabuta, Craig ;Nielsen, Blake

• Book ID: 102892728
• Publisher: John Wiley and Sons
• Year: 1982
• Tongue: English
• Weight: 762 KB
• Volume: 219
• Category: Article
• ISSN: 0022-104X
• DOI: 10.1002/jez.1402190312

✦ Synopsis

Abstract

The electrophoretic pattern of G6PD changes in sea urchin egg supernatants, gels, and pellets (homogenized in 0.01 M MgCl~2~, 0.01 M Tris, pH 8, and centrifuged at 4 × 10^4^g) within the first minute following sperm penetration. Therefore, the changes in pattern are an early event of egg activation and are not changes in gene activity. Calcium ionophore activation causes similar changes in G6PD in unfertilized eggs, so calcium is probably involved directly or indirectly. Treatment with 1 mg/ml of G6P and/or NADP, DTT, or papain also causes changes in the isozyme patterns, but the resulting patterns are different from patterns obtained from the fertilized fractions, and each treatment produces a unique pattern. The results lead to the conclusion that the different patterns of unfertilized and fertilized eggs are due to enzyme posttranslational modification. Different patterns may result from intrinsic differences in (1) —SH reduction or levels of glutathione, (2) substrate and cofactor levels, or (3) proteolytic enzymes released naturally or as a result of homogenization.