玉米精细胞质膜68 kD特异糖蛋白组分的纯化和N-端序列测定

Purification and Amino_terminal Sequencing of a 68 kD Glycopolypeptide of the Plasma Membrane from Maize Sperm Cells 

经ＳＤＳ＿ＰＡＧＥ和ＩＥＦ＿ＳＤＳ双向电泳，从玉米（ＺｅａｍａｙｓＬ．）精细胞质膜分离纯化得到等电点（ｐＩ）为５．５的６８ｋＤ糖蛋白的单一组分。伴刀豆球蛋白＿辣根过氧化物酶（ＣｏｎＡ＿ＨＲＰ）染色结果表明，该组分的糖链中含有甘露糖及葡萄糖残基。氨基酸序列分析表明，该组分的Ｎ＿端１５个氨基酸序列与ＣｏｎＡ的Ｎ＿端相应序列相同。根据分子量及ｐＩ值的差异，认为该组分并非ＣｏｎＡ，而可能与玉米精细胞质膜上的ＣｏｎＡ受体有关。它在玉米的精卵识别、粘附及融合中有何作用，无疑是令人感兴趣的问题。

Based on author's previous work on detection and immunolocalization of glycoproteins of the plasma membrane of maize (Zea mays L.) sperm cells, a 68 kD peripheral specific glycopolypeptide of the plasma membrane from maize sperm cells was purified by IEF_SDS two_dimensional electrophoresis. It presents specifically positive reaction in Con A_HRP (concanavalin A_horseradish peroxidase) staining, and its pI value is 5.5. The search in protein sequence database reveals that the amino_terminal sequence of this glycopolypeptide is identical with that of Con A. But its difference from Con A in molecular weight and pI value indicates that it could be related to a Con A receptor on the plasma membranes of maize sperm cells instead of being Con A itself. lt is fascinating to study further the function of the above glycopolypeptide in gametic recognition, adhesion and fusion of the double fertilization in maize.