Couchman J R, Kapoor R, Sthanam M, Wu R R
Department of Cell Biology, University of Alabama at Birmingham, Birmingham, Alabama 35294.
J Biol Chem. 1996 Apr 19;271(16):9595-602. doi: 10.1074/jbc.271.16.9595.
The presence of proteoglycans bearing galactosaminoglycan chains has been reported, but none has been identified previously in the matrix of the Engelbreth-Holm-Swarm tumor, which is a source of several basement membrane components. This tumor matrix contains perlecan, a large, low buoyant density heparan sulfate proteoglycan, widespread in many basement membranes and connective tissues. We now identify two distinct proteoglycan species from this tumor source, which are substituted with galactosaminoglycans and which show basement membrane localization by immunohistochemistry. One species is perlecan but, in addition to being present as a heparan sulfate proteoglycan, it is also present as a hybrid molecule, with dermatan sulfate chains. A minor population of perlecan apparently lacks heparan sulfate chains totally, and some of this is substituted with chondroitin sulfate. The second species is immunologically related to basement membrane-chondroitin sulfate proteoglycan (BM-CSPG) and bears chondroitin sulfate chains. No BM-CSPG was detectable which was substituted with heparan sulfate chains. A combination of immunological and molecular approaches, including cDNA cloning, showed that perlecan and BM-CSPG are distinct in core protein structure. Both are, however, basement membrane components, although there are tissue-specific differences in their distribution.
已有报道称存在带有半乳糖胺聚糖链的蛋白聚糖，但此前在Engelbreth-Holm-Swarm肿瘤的基质中尚未发现，该肿瘤是多种基底膜成分的来源。这种肿瘤基质含有基底膜蛋白聚糖，它是一种大型、低浮力密度的硫酸乙酰肝素蛋白聚糖，广泛存在于许多基底膜和结缔组织中。我们现在从这种肿瘤来源中鉴定出两种不同的蛋白聚糖，它们被半乳糖胺聚糖取代，并通过免疫组织化学显示出基底膜定位。一种是基底膜蛋白聚糖，但除了以硫酸乙酰肝素蛋白聚糖的形式存在外，它还以一种杂合分子的形式存在，带有硫酸皮肤素链。一小部分基底膜蛋白聚糖显然完全缺乏硫酸乙酰肝素链，其中一些被硫酸软骨素取代。第二种与基底膜硫酸软骨素蛋白聚糖（BM-CSPG）在免疫上相关，并带有硫酸软骨素链。未检测到被硫酸乙酰肝素链取代的BM-CSPG。包括cDNA克隆在内的免疫和分子方法相结合表明，基底膜蛋白聚糖和BM-CSPG在核心蛋白结构上是不同的。然而，两者都是基底膜成分，尽管它们在分布上存在组织特异性差异。
