Campbell S C, Schwartz N B
Department of Pediatrics, Joseph P. Kennedy, Jr. Mental Retardation Research Center, University of Chicago, Illinois 60637.
J Cell Biol. 1988 Jun;106(6):2191-202. doi: 10.1083/jcb.106.6.2191.
Pulse-chase labeling techniques are used in conjunction with subcellular fractionation and quantitative immunoprecipitation to define the kinetics of intracellular translocation and secretion of proteoglycan core protein, along with link protein and type II collagen. In embryonic chick chondrocytes the core protein is processed very rapidly, exhibiting a t 1/2 in both the rough endoplasmic reticulum and golgi region of less than 10 min. Link protein appears to be processed as rapidly as the core protein, but the kinetics of type II collagen secretion is 3-4 times slower. These results are consistent with possible segregation and coordinate intracellular processing of link protein and core protein, macromolecules which are known to associate extracellularly. In contrast, rat chondrosarcoma chondrocytes translocated and secreted the core protein much more slowly (t 1/2 = 40 min) than the chick cells, perhaps due to the significantly reduced levels of galactosyltransferase I observed in the transformed chondrocytes.
脉冲追踪标记技术与亚细胞分级分离和定量免疫沉淀相结合，用于确定蛋白聚糖核心蛋白以及连接蛋白和II型胶原蛋白在细胞内转运和分泌的动力学。在胚胎鸡软骨细胞中，核心蛋白加工非常迅速，在内质网和高尔基体区域的半衰期均小于10分钟。连接蛋白的加工速度似乎与核心蛋白一样快，但II型胶原蛋白的分泌动力学要慢3 - 4倍。这些结果与连接蛋白和核心蛋白可能的分离以及细胞内的协同加工一致，这两种大分子在细胞外已知会相互结合。相比之下，大鼠软骨肉瘤软骨细胞转运和分泌核心蛋白的速度比鸡细胞慢得多（半衰期 = 40分钟），这可能是由于在转化的软骨细胞中观察到的半乳糖基转移酶I水平显著降低所致。
