Iwata M, Wight T N, Carlson S S
Department of Physiology and Biophysics, University of Washington, Seattle 98195.
J Biol Chem. 1993 Jul 15;268(20):15061-9.
Unlike many tissues, the adult central nervous system extracellular matrix (ECM) has few known components. Previously, we characterized a large chondroitin sulfate proteoglycan, pgT1, from adult rat brain which has the properties of a general brain ECM component and is immunologically distinct from aggrecan and versican (Iwata, M., and Carlson, S.S. (1993) J. Neurosci. 13, 195-207). In this study we demonstrate that pgT1 binds hyaluronan with relatively high affinity. The pgT1 preparation isolated from rat brain aggregates in non-denaturing conditions. This aggregation is abolished by incubation of pgT1 with Streptomyces hyaluronidase. Examination of these aggregates by electron microscope reveals a structure in which an average of 18 subunits arise laterally from opposite sides of an elongated 350-nm filament. These pgT1 aggregates resemble the proteoglycan aggregates in cartilage which are composed of aggrecan and hyaluronan. Using affinity coelectrophoresis, we measure a dissociation constant (Kd) of 0.9 +/- 0.2 nM for the interaction of pgT1 and hyaluronan. These new findings, combined with the general distribution of pgT1 in brain, suggest that pgT1/hyaluronan aggregates are an extended general structure of the brain extracellular matrix network.
与许多组织不同，成体中枢神经系统的细胞外基质（ECM）已知成分很少。此前，我们从成年大鼠脑中鉴定出一种大型硫酸软骨素蛋白聚糖pgT1，它具有一般脑ECM成分的特性，并且在免疫上与聚集蛋白聚糖和多功能蛋白聚糖不同（岩田，M.，和卡尔森，S.S.（1993年）《神经科学杂志》13卷，195 - 207页）。在本研究中，我们证明pgT1以相对较高的亲和力结合透明质酸。从大鼠脑分离的pgT1制剂在非变性条件下会聚集。用链霉菌透明质酸酶孵育pgT1可消除这种聚集。通过电子显微镜检查这些聚集体发现，一种结构中平均有18个亚基从一条350纳米长细丝相对的两侧横向伸出。这些pgT1聚集体类似于软骨中由聚集蛋白聚糖和透明质酸组成的蛋白聚糖聚集体。使用亲和共电泳，我们测得pgT1与透明质酸相互作用的解离常数（Kd）为0.9±0.2纳摩尔。这些新发现，结合pgT1在脑中的普遍分布，表明pgT1/透明质酸聚集体是脑细胞外基质网络一种扩展的一般结构。
