Stuart S G, Trounstine M L, Vaux D J, Koch T, Martens C L, Mellman I, Moore K W
Department of Immunology, DNAX Research Institute of Molecular and Cellular Biology, Inc., Palo Alto, California 94304.
J Exp Med. 1987 Dec 1;166(6):1668-84. doi: 10.1084/jem.166.6.1668.
We have cloned and expressed a cDNA encoding a human receptor for IgG (Fc gamma R) from the monocyte cell line U937. The deduced structure is a 35-kD transmembrane protein with homology to the mouse Fc[gamma 2b/gamma 1] receptor amino acid sequence of approximately 60% in the extracellular domain. The signal sequence is homologous to the mouse Fc gamma R alpha cDNA clone, while the transmembrane domain shares homology with mouse Fc gamma R beta cDNAs. The cytoplasmic domain is apparently unique. The extracellular domain shows significant homology to proteins of the Ig gene superfamily, including the human c-fms protooncogene/CSF-1 receptor. Mouse Ltk- cells transfected with the human Fc gamma R cDNA express a cell-surface receptor that selectively binds human IgG and is recognized by the anti-Fc gamma RII mAb IV.3. Antibodies against peptides derived from the human Fc gamma R sequence specifically stain U937 cells, but not an Fc gamma RII-bearing B-lymphoblastoid cell line (Daudi). These results identify the human Fc gamma RII as the homologue of mouse Fc[gamma 2b/gamma 1] R, and provide evidence for heterogeneity of Fc gamma RII expressed on monocytes and B cells.
我们从单核细胞系U937中克隆并表达了一种编码人IgG受体（FcγR）的cDNA。推导的结构是一种35kD的跨膜蛋白，其胞外结构域与小鼠Fc[γ2b/γ1]受体氨基酸序列的同源性约为60%。信号序列与小鼠FcγRα cDNA克隆同源，而跨膜结构域与小鼠FcγRβ cDNA有同源性。胞质结构域显然是独特的。胞外结构域与Ig基因超家族的蛋白质有显著同源性，包括人c-fms原癌基因/CSF-1受体。用人FcγR cDNA转染的小鼠Ltk-细胞表达一种细胞表面受体，该受体选择性结合人IgG并被抗FcγRII单克隆抗体IV.3识别。针对源自人FcγR序列的肽的抗体可特异性地对U937细胞染色，但对携带FcγRII的B淋巴母细胞系（Daudi）则无染色。这些结果确定人FcγRII是小鼠Fc[γ2b/γ1]R的同源物，并为单核细胞和B细胞上表达的FcγRII的异质性提供了证据。
