Brady S T, Lasek R J
Cell. 1981 Feb;23(2):515-23. doi: 10.1016/0092-8674(81)90147-1.
The axonal transport of two soluble enzymes of intermediary metabolism was evaluated: the nerve-specific form of the glycolytic enzyme enolase (NSE) and the brain isozyme of creatine phosphokinase (CPK). Previously, little was known about the intracellular movements of the soluble proteins of the cell. Although the soluble enzymes of glycolysis and other pathways of intermediary metabolism have been thought to be freely diffusing in the cytosol, many are required in the axonal extremities of the neuron and must be transported to the sites of utilization. Comigration of purified enzymes with radioactive polypeptides associated with specific rate components of axonal transport in two-dimensional gel electrophoresis indicates that both NSE and CPK move in the axon solely as part of the group of proteins known as slow component b (SCb) at a rate of 2 mm/day. Peptide mapping following limited proteolysis confirmed identification of NSE and CPK in SCb. Materials associated with SCb have been shown to move coherently along the axon and to behave as a discrete cellular structure, the axoplasmic matrix. Association of two soluble enzymes, NSE and CPK, with the SCb complex of proteins requires a reevaluation of the assumption that these and other soluble proteins of the axon are freely diffusible.
糖酵解酶烯醇化酶的神经特异性形式（NSE）和肌酸磷酸激酶的脑同工酶（CPK）。此前，人们对细胞中可溶性蛋白质的细胞内运动了解甚少。尽管糖酵解及其他中间代谢途径的可溶性酶被认为可在细胞质中自由扩散，但神经元的轴突末端需要许多此类酶，因此它们必须被运输到使用部位。在二维凝胶电泳中，纯化的酶与与轴突运输的特定速率成分相关的放射性多肽共迁移，这表明NSE和CPK在轴突中仅作为被称为慢成分b（SCb）的蛋白质组的一部分移动，速率为每天2毫米。有限蛋白酶解后的肽图谱分析证实了SCb中NSE和CPK的鉴定。已证明与SCb相关的物质沿轴突连贯移动，并表现为一种离散的细胞结构，即轴质基质。两种可溶性酶NSE和CPK与蛋白质的SCb复合物的结合需要重新评估轴突中这些及其他可溶性蛋白质可自由扩散的假设。
