Marston Steven B, Redwood Charles S
Imperial College London, National Heart and Lung Institute, Dovehouse St, London SW3 6LY, UK.
Circ Res. 2003 Dec 12;93(12):1170-8. doi: 10.1161/01.RES.0000105088.06696.17.
In the heart, the contractile apparatus is adapted to the specific demands of the organ for continuous rhythmic contraction. The specialized contractile properties of heart muscle are attributable to the expression of cardiac-specific isoforms of contractile proteins. This review describes the isoforms of the thin filament proteins actin and tropomyosin and the three troponin subunits found in human heart muscle, how the isoform profiles of these proteins change during development and disease, and the possible functional consequences of these changes. During development of the heart, there is a distinctive switch of isoform expression at or shortly after birth; however, during adult life, thin filament protein isoform composition seems to be stable despite protein turnover rates of 3 to 10 days. The pattern of isoforms of actin, tropomyosin, troponin I, troponin C, and troponin T is not affected by aging or heart disease (ischemia and dilated cardiomyopathy). The evidence for proteolysis of thin filament proteins in situ during ischemia and stunning is evaluated, and it is concluded that C-terminal cleavage of troponin I is a feature of irreversibly injured myocardium but may not play a role in reversible stunning.
在心脏中，收缩装置适应于该器官持续有节律收缩的特定需求。心肌的特殊收缩特性归因于收缩蛋白的心脏特异性同工型的表达。本综述描述了细肌丝蛋白肌动蛋白和原肌球蛋白的同工型以及在人类心肌中发现的三种肌钙蛋白亚基，这些蛋白的同工型谱在发育和疾病过程中如何变化，以及这些变化可能产生的功能后果。在心脏发育过程中，出生时或出生后不久会有明显的同工型表达转换；然而，在成年期，尽管蛋白质更新率为3至10天，但细肌丝蛋白同工型组成似乎是稳定的。肌动蛋白、原肌球蛋白、肌钙蛋白I、肌钙蛋白C和肌钙蛋白T的同工型模式不受衰老或心脏病（缺血和扩张型心肌病）的影响。对缺血和心肌顿抑期间细肌丝蛋白原位蛋白水解的证据进行了评估，得出的结论是，肌钙蛋白I的C末端切割是不可逆损伤心肌的一个特征，但可能在可逆性心肌顿抑中不起作用。
