B29 gene products complex with immunoglobulins on B lymphocytes.
B29 gene products complex with immunoglobulins on B lymphocytes.
复制标题
B29 基因产物与 B 淋巴细胞上的免疫球蛋白形成复合物。
DOI：
10.1073/pnas.89.2.633
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发表时间：
1992
影响因子：
11.1
通讯作者：
Kincade,PW
中科院分区：
文献类型：
--
作者：
Ishihara,K;WoodJr,WJ;Damore,M;Hermanson,GG;Wall,R;Kincade,PW
B29是一个B系特异性基因，根据序列信息预测其为免疫球蛋白（IG）超家族的跨膜成员，具有单个胞外Ig样结构域。其假定的胞质区域包含存在于CD 3和参与淋巴细胞活化的其他分子中的肽基序。亲和纯化的山羊抗体制备B29的TrpE融合蛋白，并用于研究B29在淋巴细胞上的表达。抗血清沉淀表面标记的异源二聚体从B淋巴瘤细胞。通过SDS/PAGE分析，一个为65-88 kDa（未还原）或36-47加上32-34 kDa（还原），与洗涤剂无关。一个较小的异源二聚体检测到只有用Triton去污剂提取。当使用弱去污剂毛地黄皂苷时，IgM分子被B29抗血清共沉淀。此外，cocapping实验表明，大多数B29分子与细胞表面的IG共分布。尽管早期B系细胞和浆细胞含有B29 mRNA，但仅在具有显著量的表面IG的B细胞上可检测到表面表达。表面表达是B系特异性的，包括来自突变xid小鼠的细胞和代表μ、δ、γ和α重链同种型以及κ和λ轻链类型的B细胞系。表面B29蛋白的密度与B细胞淋巴瘤亚克隆和脂多糖刺激的前B细胞的表面μ重链密度直接相关。这些研究结果表明，B29是共价连接在一个异二聚体，并与最近提出的表面IG复合物的模型是一致的。
B29 is a B-lineage-specific gene predicted from sequence information to be a transmembrane member of the immunoglobulin (Ig) superfamily, with a single extracellular Ig-like domain. Its presumptive cytoplasmic region contains a peptide motif present in CD3 and other molecules involved in lymphocyte activation. Affinity-purified goat antibodies were prepared to a TrpE fusion protein of B29 and used to study B29 expression on lymphoid cells. The antiserum precipitated surface-labeled heterodimers from B lymphoma cells. One was 65-88 kDa (unreduced) or 36-47 plus 32-34 kDa (reduced) by SDS/PAGE analysis, regardless of detergent. A smaller heterodimer was detected only with Triton detergent extraction. IgM molecules were coprecipitated by the B29 antiserum when the weak detergent digitonin was used. In addition, cocapping experiments revealed that most B29 molecules codistribute with Ig on the cell surface. Although early B-lineage cells and plasma cells contain B29 mRNA, surface expression was detectable only on B cells that had significant amounts of surface Ig. The surface expression was B-lineage-specific and included cells from mutant xid mice and B-cell lines representing mu, delta, gamma, and alpha heavy-chain isotypes and both kappa and lambda light-chain types. The density of surface B29 protein correlated directly with surface mu heavy-chain density on subclones of a B-cell lymphoma and lipopolysaccharide-stimulated pre-B cells. These findings show that B29 is covalently linked in a heterodimer and are consistent with a recently proposed model of surface Ig complexes.