MECHANISMS OF MYOFIBRILLAR PROTEIN EXPRESSION IN THE HEA

本课题旨在研究肌原纤维化的机制和调控， 和线粒体组装和降解过程中的过渡 两个稳定状态之间的心肌。 蛋白质的周转与 将研究异质速率。 主要目标是：1.以确定 无论合成速率（Rs）或周转率分数（kp）改变 在不同的生长阶段。 考虑到联合国系统的多样性， 蛋白质的周转率之一在生长过程中必然会发生变化 为了维持细胞内单个蛋白质的恒定比例， 细胞器2.在导致改变的条件下表征肌球蛋白HC ATP酶活性 推定的同工酶将根据以下方面进行表征： 氨基酸序列（有限片段化）和免疫学特性。 的 将在从一种同工酶转变期间测量分离的HC的Rs和kp 模式到另一个。 3.为了确定相对分数率是否 结构蛋白和可溶性蛋白的周转率发生变化 在加速降解过程中。 将评价蛋白质， 分子量、等电点和碳水化合物含量。 4.的作用 钙激活的中性蛋白酶（CaAp）在肌原纤维的周转将是 重新检查。 CaAp的细胞来源将通过以下方式确定： 免疫荧光 将测定肌球蛋白HC和α-辅肌动蛋白的周转 在培养的心脏细胞中，钙内流被离子载体增强后。 的 肌丝的双六边形晶格的稳定性将在以下条件下进行检查： α-辅肌动蛋白去除。5. 为了研究溶酶体蛋白酶参与 肌原纤维的降解。 将尝试检测肌球蛋白或其 制备的溶酶体组分中的高分子量降解产物 从肌肉。

In this project we propose to study the mechanism and control of myofibrillar and mitochondrial assembly and degradation during the transition of the myocardium between two steady states. The proteins which turnover with heterogeneous rates will be studied. The main objectives are: 1. To determine whether the rate of synthesis (Rs) or the fractional rate turnover (kp) change during various phases of growth. Considering the heterogeneous nature of the turnover of proteins one of the rates necessarily must be changing during growth in order to maintain a constant ratio of individual proteins within the organelle. 2. To characterize myosin HC under conditions leading to altered ATPase activity. The putative isoenzymes will be characterized with respect to amino acid sequence (limited fragmentation) and immunological properties. The Rs and kp of separated HC will be measured during transition from one isoenzyme pattern to another one. 3. To determine whether the relative fractional rates of turnover of structural proteins and those of the soluble proteins are changed during accelerated degradation. Proteins will be evaluated with respect to molecular weight, isoelectric point, and carbohydrate content. 4. The role of calcium-activated neutral protease (CaAp) in the turnover of myofibrils will be reexamined. The cellular origin of CaAp will be determined by immunofluorescence. Turnover of myosin HC and alpha-actinin will be determined in cultured heart cells after calcium influx is enhanced by an ionophore. The stability of the double hexagonal lattice of myofilaments will be examined after alpha-actinin removal. 5. To study the involvement of lysosomal proteases in the degradation of myofibrils. Attempts will be made to detect myosin or its high molecular-weight degradation products in the lysosomal fraction prepared from muscle.