Black J D, Koury S T, Bankert R B, Repasky E A
Department of Experimental Therapeutics, Roswell Park Memorial Institute, Buffalo, New York 14263.
J Cell Biol. 1988 Jan;106(1):97-109. doi: 10.1083/jcb.106.1.97.
Spectrin-like proteins are found in a wide variety of non-erythroid cells where they generally occur in the cell cortex near the plasma membrane. To determine the intracellular distribution of alpha-spectrin (alpha-fodrin) in lymphocytes, we have developed an immunoperoxidase method to localize this protein at the ultrastructural level. Of considerable interest, particularly with regard to our efforts to determine the function of spectrin in this cell type, was the finding that its subcellular localization and its relationship with the plasma membrane can vary dramatically. Based on its position in the cell, alpha-spectrin can occur in two forms in lymphocytes: one that associates closely with the plasma membrane and another that occurs at some distance from the cell periphery, either as a single large aggregate or as several smaller ones. The single large aggregate of spectrin is a stable feature in a number of lymphocyte cell lines and hybrids which were used to examine its ultrastructural characteristics. A previously undescribed cellular structure, consisting of a meshwork of spectrin filaments and membranous vesicles, was identified in these cells. This structure could be induced to dissipate in response to membrane perturbants (e.g., hyperthermia and phorbol esters, known effectors of lymphocyte function and differentiation) and the patterns resulting from the redistribution of spectrin were a reflection of those observed routinely in lymphocytes in situ. The correlation between naturally occurring spectrin localization patterns and those seen after membrane perturbation suggested the possibility that spectrin distribution is indicative of particular maturation stages or functional states in lymphocytes. The implications of these findings with regard to the role of spectrin in lymphocyte function are discussed.
血影蛋白样蛋白存在于多种非红细胞细胞中，它们通常出现在质膜附近的细胞皮质中。为了确定α-血影蛋白（α- fodrin）在淋巴细胞中的细胞内分布，我们开发了一种免疫过氧化物酶方法，以便在超微结构水平上定位这种蛋白质。特别令人感兴趣的是，尤其是就我们确定血影蛋白在这种细胞类型中的功能的努力而言，发现其亚细胞定位及其与质膜的关系可能会发生巨大变化。根据其在细胞中的位置，α-血影蛋白在淋巴细胞中可以以两种形式出现：一种与质膜紧密结合，另一种则位于离细胞周边有一定距离的位置，要么是单个大聚集体，要么是几个较小的聚集体。血影蛋白的单个大聚集体是许多淋巴细胞系和用于检查其超微结构特征的杂交细胞中的一个稳定特征。在这些细胞中鉴定出一种以前未描述过的细胞结构，它由血影蛋白细丝和膜性小泡组成的网络构成。这种结构可以被诱导因膜扰动剂（例如热疗和佛波酯，已知的淋巴细胞功能和分化的效应物）而消散，并且血影蛋白重新分布产生的模式反映了原位淋巴细胞中常规观察到的模式。天然存在的血影蛋白定位模式与膜扰动后观察到的模式之间的相关性表明，血影蛋白分布可能指示淋巴细胞中的特定成熟阶段或功能状态。讨论了这些发现对血影蛋白在淋巴细胞功能中的作用的影响。
