Samuelsson S J, Luther P W, Pumplin D W, Bloch R J
Department of Physiology, University of Maryland School of Medicine, Baltimore 21201.
J Cell Biol. 1993 Jul;122(2):485-96. doi: 10.1083/jcb.122.2.485.
We used quick-freeze, deep-etch, rotary replication and immunogold cytochemistry to identify a new structure at focal contacts. In Xenopus fibroblasts, elongated aggregates of particles project from the membrane to contact bundles of actin microfilaments. Before terminating, a single bundle of microfilaments interacts with several aggregates that appear intermittently over a distance of several microns. Aggregates are enriched in proteins believed to mediate actin-membrane interactions at focal contacts, including beta 1-integrin, vinculin, and talin, but they appear to contain less alpha-actinin and filamin. We also identified a second, smaller class of aggregates of membrane particles that contained beta 1-integrin but not vinculin or talin and that were not associated with actin microfilaments. Our results indicate that vinculin, talin, and beta 1-integrin are assembled into distinctive structures that mediate multiple lateral interactions between microfilaments and the membrane at focal contacts.
我们运用快速冷冻、深度蚀刻、旋转复型和免疫金细胞化学技术，在粘着斑处鉴定出一种新结构。在非洲爪蟾成纤维细胞中，细长的颗粒聚集体从膜上伸出，与肌动蛋白微丝束相接触。在终止之前，单束微丝与几个聚集体相互作用，这些聚集体在几微米的距离内间歇性出现。聚集体富含被认为在粘着斑处介导肌动蛋白与膜相互作用的蛋白质，包括β1整合素、纽蛋白和踝蛋白，但它们似乎含较少的α辅肌动蛋白和细丝蛋白。我们还鉴定出另一类较小的膜颗粒聚集体，其含有β1整合素，但不含纽蛋白或踝蛋白，且不与肌动蛋白微丝相关联。我们的结果表明纽蛋白、踝蛋白和β1整合素组装成独特结构，在粘着斑处介导微丝与膜之间的多种侧向相互作用。
