Yazawa M, Nakashima K, Yagi K
Division of Chemistry, Graduate School of Science, Hokkaido University, Sapporo, Japan.
Mol Cell Biochem. 1999 Jan;190(1-2):47-54.
Calmodulin of Saccharomyces cerevisiae has different Ca2+ binding properties from other calmodulins. We previously reported that the maximum number of Ca2+ binding was 3 mol/mol and the fourth binding site was defective, which was different from 4 mol/mol for others. Their macroscopic dissociation constants suggested the cooperative three Ca2+ bindings rather than a pair of cooperative two Ca2+ bindings of ordinary calmodulin. Here we present evidence for yeast calmodulin showing the intramolecular close interaction between the N-terminal half domain and the C-terminal half domain, while the two domains of ordinary calmodulin are independent of each other. We will discuss the relationship of the shape and the shape change caused by the Ca2+ binding to the enzyme activation in yeast. The functional feature of calmodulin in yeast will also be considered, which might be different from the one of vertebrate calmodulin.
酿酒酵母的钙调蛋白与其他钙调蛋白具有不同的Ca2+结合特性。我们之前报道过，其Ca2+结合的最大数量为3摩尔/摩尔，第四个结合位点存在缺陷，这与其他钙调蛋白的4摩尔/摩尔不同。它们的宏观解离常数表明存在协同的三个Ca2+结合，而不是普通钙调蛋白的一对协同的两个Ca2+结合。在这里，我们提供证据表明酵母钙调蛋白在N端半结构域和C端半结构域之间存在分子内紧密相互作用，而普通钙调蛋白的两个结构域相互独立。我们将讨论酵母中Ca2+结合导致的形状及其变化与酶激活之间的关系。还将考虑酵母中钙调蛋白的功能特性，它可能与脊椎动物钙调蛋白的功能特性不同。
