Beachy J C, Goldman D, Czech M P
Proc Natl Acad Sci U S A. 1981 Oct;78(10):6256-60. doi: 10.1073/pnas.78.10.6256.
The mitogenic lectins concanavalin A and phytohemagglutinin were found to stimulate pyruvate oxidation in rat mesenteric lymphocytes. Marked cell agglutination accompanied this response. Wheat germ agglutinin, a nonmitogenic lectin, also aggregated lymphocytes but did not cause alteration of pyruvate oxidation. Cell lysates from lectin-treated cells retained their ability to oxidize pyruvate at an elevated rate, indicating that the observed stimulation of pyruvate oxidation was not due to increased transport of labeled pyruvate into the cells. Pyruvate oxidation activity in such lysates was readily sedimented in a mitochondria-enriched cellular fraction, indicating that it reflects mitochondrial pyruvate dehydrogenase. Stimulation of this activity by lectins in intact lymphocytes was inhibited when the cells were incubated under conditions expected to inhibit trypsin-like proteases. Thus, esters of arginine, but not of alanine or tyrosine, blocked stimulation of pyruvate dehydrogenase by the lectins. The data indicate that pyruvate dehydrogenase is activated in lymphocytes treated with mitogenic lectins by a mechanism involving one or more proteolytic reactions. The similarity between the results presented here and those recently reported for insulin action on its target cells [Seals, J. R. & Czech, M. P. (1980) J. Biol. Chem. 255, 6529-6531] suggests that these systems may have similar modes of transmembrane signalling.
有丝分裂凝集素伴刀豆球蛋白A和植物血凝素可刺激大鼠肠系膜淋巴细胞中的丙酮酸氧化。这种反应伴随着明显的细胞凝集。非有丝分裂凝集素麦胚凝集素也能使淋巴细胞聚集，但不会引起丙酮酸氧化的改变。凝集素处理过的细胞的细胞裂解物仍保持以较高速率氧化丙酮酸的能力，这表明观察到的丙酮酸氧化刺激并非由于标记丙酮酸向细胞内转运增加所致。这种裂解物中的丙酮酸氧化活性很容易在富含线粒体的细胞组分中沉淀，这表明它反映的是线粒体丙酮酸脱氢酶。当细胞在预期能抑制类胰蛋白酶的条件下孵育时，凝集素对完整淋巴细胞中这种活性的刺激作用受到抑制。因此，精氨酸酯而非丙氨酸酯或酪氨酸酯可阻断凝集素对丙酮酸脱氢酶的刺激。数据表明，有丝分裂凝集素处理的淋巴细胞中的丙酮酸脱氢酶是通过涉及一种或多种蛋白水解反应的机制被激活的。此处呈现的结果与最近报道的胰岛素对其靶细胞作用的结果[西尔斯，J.R.和捷克，M.P.（1980年）《生物化学杂志》255卷，6529 - 6531页]之间的相似性表明，这些系统可能具有相似的跨膜信号传导模式。
