梨形四膜虫中的接合作用。聚赖氨酸、伴刀豆球蛋白A和二价金属对接合过程的影响。
Conjugation in Tetrahymena pyriformis. The effect of polylysine, concanavalin A, and bivalent metals on the conjugation process.
作者信息
Ofer L, Levkovitz H, Loyter A
出版信息
J Cell Biol. 1976 Aug;70(2 pt 1):287-93. doi: 10.1083/jcb.70.2.287.
The polycation polylysine, at different degrees of polymerization, was found to cause a marked inhibition of the conjugation process. Inhibition of conjugation by polylysine was highly dependent on the molecular weight of the polymer. When polylysine of a mol wt of 1,250 (degree of polymerization=6) was used, a concentration of 1.6 X 10(-5) M was required for a complete inhibition of conjugation, while only 2 X 10(-7) M of polylysine of a mol wt of 71,000 (degree of polymerization=340) was needed for the same effect. Polyaspartic acid prevented the inhibition of conjugation by polylysein. Chelators of bivalent metals such as O-phenanthroline (10(-3) M), EDTA (10(-3) M), and EGTA (5 X 10(-3) M) strongly inhibit the conjugation process in Tetrahymena pyriformis. The inhibition was partially prevented when bivalent metals such as Zn++, Fe++, and Ca++ were added together with the chelators. The lectin concanavalin A (25 mug/ml) completely prevented the conjugation process, while other lectins, such as phytohemagglutinin (500 mug/ml), soybean agglutinin (75 mug/ml) and wheat germ agglutinin (250 mug/ml) had no effect. Inhibition of conjugation by concanavalin A is completely reversible by 40 mM of alpha-methyl-D-mannoside.
研究发现，不同聚合度的聚阳离子聚赖氨酸会对结合过程产生显著抑制作用。聚赖氨酸对结合的抑制作用高度依赖于聚合物的分子量。当使用分子量为1250（聚合度 = 6）的聚赖氨酸时，完全抑制结合需要1.6×10⁻⁵ M的浓度，而对于分子量为71000（聚合度 = 340）的聚赖氨酸，达到相同效果仅需2×10⁻⁷ M。聚天冬氨酸可防止聚赖氨酸对结合的抑制。二价金属螯合剂，如邻菲罗啉（10⁻³ M）、乙二胺四乙酸（10⁻³ M）和乙二醇双四乙酸（5×10⁻³ M），能强烈抑制梨形四膜虫的结合过程。当与螯合剂一起添加二价金属如锌离子、亚铁离子和钙离子时，这种抑制作用会部分得到缓解。凝集素伴刀豆球蛋白A（25 μg/ml）能完全阻止结合过程，而其他凝集素，如植物血凝素（500 μg/ml）、大豆凝集素（75 μg/ml）和麦胚凝集素（250 μg/ml）则没有作用。伴刀豆球蛋白A对结合的抑制作用可被40 mM的α-甲基-D-甘露糖苷完全逆转。
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