Härtner K T, Pette D
Fakultät für Biologie, Universität Konstanz, Federal Republic of Germany.
Eur J Biochem. 1990 Mar 10;188(2):261-7. doi: 10.1111/j.1432-1033.1990.tb15398.x.
Polyclonal antibodies were raised against troponin I (TnI) and troponin C (TnC) purified from fast-twitch and slow-twitch rabbit muscles. These antibodies were used to elucidate the distribution of fast and slow isoforms of TnI and TnC in normal and chronically stimulated rabbit hind limb muscles by immunoblots of one-dimensional and two-dimensional electrophoreses. In contrast to the multiplicity of fast and slow troponin T (TnT) isoforms, TnI and TnC were present as unique fast and slow isoforms. Whereas no charge variants were detected for slow TnI, fast TnI was present in at least three charge variants. As judged from the results of alkaline phosphatase digestion, these charge variants represent differently phosphorylated forms. Fast and slow TnC both exist as two charge variants which, however, were unaffected by alkaline phosphatase treatment. Chronic low-frequency stimulation of fast-twitch muscles induced progressive increases in the slow isoforms of TnC and TnI at the expense of their fast isoforms. The extent of the fast-to-slow transition was more pronounced in the case of TnC than in that of TnI. Long-term stimulated muscles with a complete fast-to-slow transition, at the level of the TnT isoforms, still contained fast and slow isoforms of both TnI and TnC. The coexistence of fast and slow isoforms of the three troponin subunits in the transforming muscle was interpreted as indicating the presence of hybrid troponin molecules composed of fast and slow isoforms. Studies at the mRNA level showed changes similar to those at the protein level. However, in long-term stimulated muscles, the fast-to-slow transition of TnI was more pronounced at the mRNA level than at the protein level.
制备了针对从快肌和慢肌兔肌肉中纯化的肌钙蛋白I（TnI）和肌钙蛋白C（TnC）的多克隆抗体。通过一维和二维电泳免疫印迹法，使用这些抗体来阐明TnI和TnC的快、慢同工型在正常和慢性刺激的兔后肢肌肉中的分布。与快、慢肌钙蛋白T（TnT）同工型的多样性不同，TnI和TnC以独特的快、慢同工型形式存在。慢TnI未检测到电荷变体，而快TnI至少以三种电荷变体形式存在。从碱性磷酸酶消化结果判断，这些电荷变体代表不同的磷酸化形式。快、慢TnC均以两种电荷变体形式存在，然而，它们不受碱性磷酸酶处理的影响。对快肌进行慢性低频刺激导致TnC和TnI的慢同工型逐渐增加，同时快同工型减少。TnC从快到慢的转变程度比TnI更明显。在TnT同工型水平上具有完全从快到慢转变的长期刺激肌肉，仍然含有TnI和TnC的快、慢同工型。在转化肌肉中三种肌钙蛋白亚基的快、慢同工型共存被解释为表明存在由快、慢同工型组成的杂交肌钙蛋白分子。mRNA水平的研究显示出与蛋白质水平相似的变化。然而，在长期刺激的肌肉中，TnI从快到慢的转变在mRNA水平上比在蛋白质水平上更明显。
