Andres J L, Stanley K, Cheifetz S, Massagué J
Cell Biology and Genetics Program, Memorial Sloan-Kettering Cancer Center, New York 10021.
J Cell Biol. 1989 Dec;109(6 Pt 1):3137-45. doi: 10.1083/jcb.109.6.3137.
Transforming growth factors beta 1 and beta 2 bind with high affinity to the core protein of a 250-350-kD cell surface proteoglycan. This proteoglycan (formerly referred to as the type III TGF-beta receptor) coexists in many cells with the receptor implicated in TGF-beta signal transduction (type I TGF-beta receptor), but its function is not known. We report here that soluble TGF-beta-binding proteoglycans are released by several cell types into the culture media, and can be found in serum and extracellular matrices. As has been shown for the membrane-bound form, the soluble proteoglycans have a heterogeneous core protein of 100-120 kD that carries chondroitin sulfate and/or heparan sulfate glycosaminoglycan chains and a small amount of N-linked carbohydrate. The membrane-bound form of this proteoglycan is hydrophobic and associates with liposomes, whereas the soluble forms lack a membrane anchor and do not associate with liposomes. Differences in the electrophoretic migration of the soluble and membrane forms of this proteoglycan suggest additional structural differences in their core proteins and glycosaminoglycan chains. These soluble and membrane-bound proteoglycans, for which we propose the name "betaglycans," might play distinct roles in pericellular retention, delivery, or clearance of activated TGF-beta.
转化生长因子β1和β2与一种250 - 350kD细胞表面蛋白聚糖的核心蛋白高亲和力结合。这种蛋白聚糖（以前称为III型TGF-β受体）在许多细胞中与参与TGF-β信号转导的受体（I型TGF-β受体）共存，但其功能尚不清楚。我们在此报告，可溶性TGF-β结合蛋白聚糖由几种细胞类型释放到培养基中，并且可以在血清和细胞外基质中发现。正如膜结合形式所显示的那样，可溶性蛋白聚糖具有100 - 120kD的异质性核心蛋白，其携带硫酸软骨素和/或硫酸乙酰肝素糖胺聚糖链以及少量N - 连接碳水化合物。这种蛋白聚糖的膜结合形式具有疏水性并与脂质体结合，而可溶性形式缺乏膜锚定且不与脂质体结合。这种蛋白聚糖的可溶性和膜结合形式在电泳迁移上的差异表明它们的核心蛋白和糖胺聚糖链存在其他结构差异。我们提议将这些可溶性和膜结合的蛋白聚糖命名为“β聚糖”，它们可能在细胞周围对活化TGF-β的保留、传递或清除中发挥不同作用。
