FUNCTION AND ISOFORMS OF SECRETORY PATHWAY CALCIUM PUMP

细胞内游离钙浓度([Ca~(2+)]i)的精确控制是 细胞内钙离子作为第二信使发挥作用的先决条件。 肌浆网和血浆中的Ca~(2+)-ATPase 膜(PMCA)在这种控制和维护中起着至关重要的作用 [Ca~(2+)]i.似乎编码第三个不同类别的cdna，分泌型 钙-ATPase通路{SPCA}已被发现，哺乳动物高尔基体和 脑突触小泡含有一种具有鲜明特征的钙-ATPase 与PMCA和SERCA的情况不同。我们建议获取详细的 通过以下方式了解SPCA的功能完整性和遗传多样性 该酶在哺乳动物组织培养中的瞬时稳定表达 细胞及其与脑内钙泵特性的比较 分泌细胞中的突触小泡和高尔基体膜。这个 编码任何其他SPCA亚型的基因的相应cDNA，这些亚型可能 存在于哺乳动物中的基因组将被分离并利用 聚合酶链式反应、Northern和Southern杂交技术及其组织分布 他们的mRNAs将被评估。这些将提供对以下角色的深入了解 囊泡内钙离子对膜萌发和融合的调控作用 水泡运输以及由此导致的疾病信息 由分泌组织的无效功能引起。

The precise control of intracellular free Ca2+-concentration ([Ca2+]i) is a prerequisite for the function of Ca2+ as a second messenger in cells. Ca2+-ATPases of sarco (endo) plasmic reticulum (SERCAs) and plasma membranes (PMCA) play crucial roles in this control and maintenance of the [Ca2+]i. A cDNA that seems to encode a third distinct class, secretory pathway Ca2+-ATPases {SPCA} has been identified and mammalian Golgi and brain synaptic vesicles contain a Ca2+-ATPase with distinct characteristics from those of pMCAs and SERCAs. We propose to obtain a detailed understanding of the functional integrity and genetic diversity of SPCA by expressing the enzyme transiently and stably in mammalian tissue culture cells and comparing its properties with those of the Ca2+-pump of the brain synaptic vesicles and Golgi membranes in secretory cells. The corresponding cDNAs of genes encoding any additional SPCA isoforms that may exist in mammalian genome will be isolated and characterized by utilizing PCR, northern and Southern blot techniques and the tissue distribution of their mRNAs will be assessed. These will provide insight into the role of intravesicular Ca2+ in the control of membrane budding and fusion during vesicle trafficking and hence Information regarding diseases that result from ineffective functioning of secretory tissues.