Mechanisms of Na and Ca Transport Across the Plasma Membranes of Squid Giant Axons, Structure-Function Relationships

细胞的内部相对于细胞是电负性的。 细胞外介质。 然而，与自然趋势相反， 带正电荷的Na和Ca离子聚集到 细胞，它们更集中在外侧。 到 保持这种情况，净稳定Na和Ca挤出必须 在消耗能量的同时发生。 对于Ca，两种蛋白质 位于质膜上的Ca~（2+）和Ca~（2+）相互作用， 泵，其使用来自ATP水解的能量，和（ii）Na/Ca 虽然它需要来自内在的能量， 梯度，也受到ATP的刺激。 这些研究将 表征Na/Ca的结构-功能关系 交换器采用鱿鱼巨大的轴突。 在透析下， 制备是独特的，因为它允许几乎完全的生物化学 控制细胞内和细胞外环境， 跨膜电位 以下问题的答案 具体的问题，可以预期提供一个增加我们的 了解如何非凡的电化学障碍， 他们的行动 (i)ATP刺激是直接作用于 交换器或其他结构，可能激酶，参与？ (ii)哪些氨基酸（蛋白质的结构单位）是相关的 交换机的功能？ 在这种情况下， 选择性地阻断不同的氨基酸或化学基团， 将用于钙挤压的生理相关性 系统的事实证明，细胞内的<$Ca! 调节血液流量和压力以及神经和内分泌 功能协调发展的

The interior of the cells is electronegative respect to the extracellular media. However, against the natural tendency of the positively charged Na and Ca ions to accumulate into the cells, they are much more concentrated in the external side. To maintain that situation a net steady Na and Ca extrusion must take place while energy is consumed. For Ca, two proteins located in the plasma membrane cooperate to that end: (i) the Ca pump, which uses energy from ATP hydrolysis, and (ii) the Na/Ca exchange which, though it takes that energy from the inward Na gradient, is also stimulated by ATP. The studies will characterize the structure-function relationships of the Na/Ca exchanger employing the squid giant axon. Under dialysis, this preparation is unique for it allows almost complete biochemical control of intra and extracellular environments and also of the transmembrane electrical potential. Answers to the following specific questions can be expected to provide an increase in our understanding of how extraordinary electrochemical barriers to their movements. (i) Is ATP stimulation is exerted directly on the exchanger or are other structures, perhaps kinases, involved? (ii) What amino acids (structural units of proteins) are relevant to the functions of the exchanger? In this case compounds known to selectively block different amino acids or chemical groups will be used. The physiological relevance of the Ca extruding systems is evidenced by the fact that intracellular ıCa! regulated blood flow and pressure and neural and endocrine functions.