DISTINCT AND OVERLAPPING LIGAND SPECIFICITIES OF THE ALPHA-3A-BETA-1 AND ALPHA-6A-BETA-1 INTEGRINS - RECOGNITION OF LAMININ ISOFORMS
DISTINCT AND OVERLAPPING LIGAND SPECIFICITIES OF THE ALPHA-3A-BETA-1 AND ALPHA-6A-BETA-1 INTEGRINS - RECOGNITION OF LAMININ ISOFORMS
复制标题
DOI：
10.1091/mbc.5.2.203
复制
发表时间：
1994-02-01
影响因子：
3.3
通讯作者：
SONNENBERG, A
中科院分区：
文献类型：
--
作者：
DELWEL, GO;DEMELKER, AA;SONNENBERG, A
利用转染全长alpha3A cDNA的K562细胞分析alpha3Abeta1整合素的配体特异性，并与同样转染的K562细胞中的alpha6Abeta1进行比较。获得的克隆在表面表达alpha3Abeta1和alpha6Abeta1整合素。那些表达alpha3Abeta1的细胞附着并扩散在免疫纯化的人钾素和含有人钾素的细胞基质上，钾素是层粘连蛋白的一种特殊亚型。此外，在牛肾层粘连蛋白上发现了一种新的a链变体。针对钾素a链成分的单克隆抗体可阻断其与钾素的结合，抗α 3和β 1单克隆抗体可阻断其与钾素和肾层粘连蛋白的粘附。经α 1刺激抗体TS2/16处理后，转染α 3 a的细胞与钾素和牛肾层粘连蛋白结合更强。α - 3a转染物对具有Am链变体（merosin）的人胎盘层粘连蛋白具有明显较弱的激活依赖性粘附，而对牛心脏层粘连蛋白和小鼠EHS肿瘤层粘连蛋白没有粘附。其他无活性底物是纤维连接蛋白、氮原蛋白和IV型和VI型胶原蛋白，这表明alpha3Abeta1整合素是一个比之前认为的要少得多的混杂受体。相比之下，在TS2/16刺激下，转染alpha6A的细胞粘附在所有层粘连蛋白亚型上。在没有TS2/16的情况下，粘附也仅发生在牛肾层粘连蛋白上。这些结果表明，alpha3Abeta1和alpha6Abeta1整合素都是典型的层粘连蛋白受体，但它们与各种层粘连蛋白异构体结合的亲和力和激活依赖性有很大差异。
The ligand specificity of the alpha3Abeta1 integrin was analyzed using K562 cells transfected with full-length alpha3A cDNA and was compared with that of alpha6Abeta1 in similarly transfected K562 cells. Clones were obtained that showed comparable surface expression of either alpha3Abeta1 or alpha6Abeta1 integrins. Those expressing alpha3Abeta1 attached to and spread on immunopurified human kalinin and cellular matrices containing human kalinin, which is a particular isoform of laminin. In addition, alpha3A transfectants adhered to bovine kidney laminins possessing a novel A chain variant. Binding to kalinin was blocked by a monoclonal antibody against the A chain constituent of kalinin and adhesion to both kalinin and kidney laminins by anti-alpha3 and beta1 monoclonal antibodies. The alpha3A transfected cells bound more strongly to kalinin and bovine kidney laminins after treatment with the beta1 stimulatory antibody TS2/16. A distinctly weaker and activation-dependent adhesion of alpha3A transfectants was observed on human placental laminins possessing the Am chain variant (merosin), and no adhesion occurred on bovine heart laminins and murine EHS tumor laminin. Further inactive substrates were fibronectin, nidogen, and collagen types IV and VI, indicating that the alpha3Abeta1 integrin is a much less promiscuous receptor than thought before. By contrast, alpha6A transfected cells adhered to all laminin isoforms when stimulated with TS2/16. Adhesion also occurred only on bovine kidney laminins in the absence of TS2/16. These results demonstrate that both alpha3Abeta1 and alpha6Abeta1 integrins are typical laminin receptors but that their affinity and activation dependence for binding to various laminin isoforms differ considerably.