Tartour E, de la Salle H, de la Salle C, Teillaud C, Camoin L, Galinha A, Latour S, Hanau D, Fridman W H, Sautès C
INSERM U.255, Institut Curie, Paris, France.
Int Immunol. 1993 Aug;5(8):859-68. doi: 10.1093/intimm/5.8.859.
Low affinity Fc gamma R are a heterogeneous group of glycoproteins which exist in transmembrane (TM) as well as in soluble forms. Two membrane isoforms of the murine type II Fc gamma R, Fc gamma RIIb1 and Fc gamma RIIb2, have been described. They result from the translation of alternatively spliced pre-mRNA, Fc gamma RIIb2 lacking sequences of the first intracytoplasmic domain (IC1). Soluble forms of Fc gamma R (sFc gamma R) have previously been shown to result from proteolysis of membrane receptors. We report here the identification, in macrophages, of a mRNA derived from the Fc gamma RII gene by splicing exons encoding the TM and IC1 domains, i.e. corresponding to a TM-deleted Fc gamma RIIb2 mRNA. A soluble protein possibly encoded by this mRNA was identified in macrophage supernatants. In accordance with Fc gamma R nomenclature, we propose to name this new Fc gamma RII isoform Fc gamma RIIb3. It is the most abundant sFc gamma R present in serum, as compared with sFc gamma R resulting from cleavage of membrane Fc gamma R.
低亲和力FcγR是一组异质性糖蛋白，以跨膜（TM）形式和可溶性形式存在。已描述了小鼠II型FcγR的两种膜异构体，即FcγRIIb1和FcγRIIb2。它们是由选择性剪接的前体mRNA翻译产生的，FcγRIIb2缺少第一个胞质内结构域（IC1）的序列。FcγR的可溶性形式（sFcγR）先前已被证明是膜受体蛋白水解的结果。我们在此报告，在巨噬细胞中鉴定出一种源自FcγRII基因的mRNA，它通过剪接编码TM和IC1结构域的外显子产生，即对应于缺失TM的FcγRIIb2 mRNA。在巨噬细胞上清液中鉴定出一种可能由该mRNA编码的可溶性蛋白。根据FcγR命名法，我们建议将这种新的FcγRII异构体命名为FcγRIIb3。与膜FcγR裂解产生的sFcγR相比，它是血清中含量最丰富的sFcγR。
