MECHANISMS OF FORMATION OF IGE-BINDING FACTORS (SOLUBLE CD23) .1. FC-EPSILON-R-II BEARING B-CELLS GENERATE IGE-BINDING FACTORS OF DIFFERENT MOLECULAR-WEIGHTS
MECHANISMS OF FORMATION OF IGE-BINDING FACTORS (SOLUBLE CD23) .1. FC-EPSILON-R-II BEARING B-CELLS GENERATE IGE-BINDING FACTORS OF DIFFERENT MOLECULAR-WEIGHTS
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DOI：
10.1016/0161-5890(89)90054-0
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发表时间：
1989-12-01
影响因子：
3.6
通讯作者：
DELESPESSE, G
中科院分区：
文献类型：
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作者：
LETELLIER, M;SARFATI, M;DELESPESSE, G
免疫球蛋白结合因子(可溶性CD23)通常被认为具有25,000-27,000的MR。本研究首先指出，根据培养条件和Fc.epsilon.R II细胞的性质，Fc.epsilon.R II也可能产生MR为33,000或37,000的IgE-BF。延续我们之前的观察，即MR 25,000-27,000 IgE-BF来自于可溶性MR 37,000前体的切割，我们在这里表明这种切割被碘乙酰胺特异性地抑制，而不是被其他几种蛋白酶抑制剂抑制。参与将33,000-37,000个MR前体裂解成25,000-27,000个MR IgE-BF的蛋白水解酶是与细胞相关的，并且特异地表达在FC.epsilon II承载细胞上。不出所料，Fc.epsilon.R II的这33,000和37,000个MR片段通过测定它们的氨基末端序列来定位。MR 37,000个IgE-BF开始于Fc.epsilon.R II序列的第81位(谷氨酰胺)，而MR 33,000个IgE-BF开始于第102位(亮氨酸)。综上所述，本研究不仅有助于我们了解IgE-BF的形成机制，而且为制备具有不同生物活性的不同分子形式的IgE-BF提供了一种手段。
IgE-binding factors (soluble CD23) are generally considered to have an Mr of 25,000-27,000. The present study first indicates that IgE-BFs with an Mr of 33,000 or 37,000 may also be produced by Fc.epsilon.R II bearing B cells, depending upon the culture conditions and the nature of the Fc.epsilon.R II bearing cells. Extending our previous observations that the Mr 25,000-27,000 IgE-BFs are derived from the cleavage of soluble Mr 37,000 precursors, we show here that this cleavage is specifically inhibited by iodoacetamide but not by several other protease inhibitors. The proteolytic enzyme involved in the cleavage of Mr 33,000-37,000 precursors into Mr 25,000-27,000 IgE-BFs is cell-associated and is specifically expressed on Fc.epsilon.R II bearing cells. As expected, these Mr 33,000 and 37,000 fragments of Fc.epsilon.R II was located by determining their amino-terminal sequence. The Mr 37,000 IgE-BFs start at position 81 (glutamine) and the Mr 33,000 IgE-BFs start at position 102 (leucine) of the Fc.epsilon.R II sequence. Taken collectively, the present study not only contributes to our understanding of the mechanisms of formation of IgE-BFs, but also provides a means to prepare different molecular forms of IgE-BFs which may display different biological activity.