mRNA for surface immunoglobulin gamma chains encodes a highly conserved transmembrane sequence and a 28-residue intracellular domain.
mRNA for surface immunoglobulin gamma chains encodes a highly conserved transmembrane sequence and a 28-residue intracellular domain.
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表面免疫球蛋白 γ 链的 mRNA 编码高度保守的跨膜序列和 28 个残基的胞内结构域。
DOI：
10.1073/pnas.79.6.2008
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发表时间：
1982
影响因子：
11.1
通讯作者：
Bernard,O
中科院分区：
文献类型：
--
作者：
Tyler,BM;Cowman,AF;Gerondakis,SD;Adams,JM;Bernard,O
为了探究膜 IgG 的 γ 重链的结构以及编码它的 mRNA 和基因片段，我们分析了源自 B 淋巴瘤 2PK-3 的 γ 1 膜 RNA 的 cDNA 克隆。克隆的核苷酸序列表明，膜γ1链具有分泌性γ1链中不存在的COOH末端71残基片段。该末端包括与膜 mu 链同源的 26 个残基的疏水跨膜区，并且重要的是，仅在 γ 链上发现的 28 个残基的胞内结构域。额外的结构域表明，记忆 B 细胞上的受体 IgG 在结合抗原时可能会产生与原始 B 细胞上的受体 IgM 不同的信号。 γ 1 膜末端由 C γ 1 基因下游 1.5 和 2.4 千碱基对的两个基因片段编码，同源片段出现在 C γ 2a 和 C γ 3 基因的 3' 处。少量的膜 γ mRNA 持续存在于分泌 IgG1、IgG2a 或 IgG2b 的浆细胞瘤中，表明替代 RNA 加工途径之间的竞争控制着膜和分泌性 γ 链 mRNA 的合成。
To probe the structure of the gamma heavy chain of membrane IgG and the mRNA and gene segments that encode it, we have analyzed cDNA clones derived from a gamma 1 membrane RNA of B lymphoma 2PK-3. The nucleotide sequence of the clones indicated that membrane gamma 1 chains bear a COOH-terminal 71-residue segment that is absent from secretory gamma 1 chains. This terminus includes a 26-residue hydrophobic transmembrane region homologous to that of membrane mu chains and, significantly, a 28-residue intracellular domain found only on gamma chains. The extra domain suggests that receptor IgG, on memory B cells, may generate a different signal on binding antigen than does receptor IgM, on virgin B cells. The gamma 1 membrane terminus is encoded by two gene segments 1.5 and 2.4 kilobase pairs downstream from the C gamma 1 gene, and homologous segments occur 3' to the C gamma 2a and C gamma 3 genes. Small amounts of membrane gamma mRNAs persist in plasmacytomas secreting IgG1, IgG2a, or IgG2b, suggesting that competition between alternative RNA processing pathways governs the synthesis of membrane and secretory gamma chain mRNAs.