Calcium‐Dependent Binding of Cytosolic Proteins by Chromaffin Granules from Adrenal Medulla
Calcium‐Dependent Binding of Cytosolic Proteins by Chromaffin Granules from Adrenal Medulla
复制标题
肾上腺髓质嗜铬颗粒与胞浆蛋白的钙依赖性结合
DOI：
10.1111/j.1471-4159.1982.tb06656.x
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发表时间：
1982
影响因子：
4.7
通讯作者：
R. Burgoyne
中科院分区：
文献类型：
--
作者：
M. Geisow;R. Burgoyne
摘要：来自牛肾上腺髓质的纯化嗜铬颗粒在微摩尔水平的Ca 2+和生理水平的K+、Mg 2+和Mg-ATP下结合一小组髓质细胞胞质溶胶蛋白。结合蛋白在十二烷基硫酸钠-聚丙烯酰胺凝胶电泳上的分子量为33，000 - 37，000和70，000 - 71，000，与任何先前报道的嗜铬细胞胞质组分不一致。在0.1 μM Ca 2+浓度下，新蛋白质从完整颗粒或重新密封的颗粒膜中洗脱;在2.6 μM浓度下，结合率达到最大值的一半。以这种方式的吸附和洗脱导致新蛋白质的高度纯化，这些新蛋白质是原始胞质溶胶的次要组分。富含33，000 - 37，000和70，000 - 71，000蛋白质的部分纯化的级分在存在毫摩尔Mg 2+的情况下以亚微摩尔水平结合45 Ca 2+。钙调素也结合的颗粒膜，并存在于微量的细胞溶质洗脱液从颗粒，但它不结合新的蛋白质在钙离子的存在下。新的蛋白质可能的意义，从嗜铬细胞的钙介导的分泌进行了讨论。
Abstract: Purified chromaffin granules from bovine adrenal medulla bound a small group of medullary cell cytosol proteins at micromolar levels of Ca2+ and physiological levels of K+, Mg2+, and Mg‐ATP. The bound proteins had molecular weights of 33,000‐37,000 and 70,000‐71,000 on sodium dodecyl sulphate‐polyacrylamide gel electrophoresis and did not correspond with any previously reported cytosolic components of chromaffin cells. The new proteins were eluted from intact granules or resealed granule membranes at 0.1 μM Ca2+; binding was half‐maximal at 2.6 μM. Adsorption and elution in this manner resulted in a high degree of purification of the new proteins that were minor components of the original cytosol. Partially purified fractions enriched in the 33,000‐37,000 and 70,000‐71,000 proteins bound 45Ca2+ at submicromolar levels in the presence of millimolar Mg2+. Calmodulin was also bound by the granule membranes and was present in trace amounts in cytosol eluates from granules, but it did not bind to the new proteins in the presence of calcium ions. The possible significance of the new proteins to calcium‐mediated secretion from chromaffin cells is discussed.