Frémont P, Lazure C, Tremblay R R, Chrétien M, Rogers P A
Muscle Biology Research Group, Laval University, Ste-Foy, Que., Canada.
Biochem Cell Biol. 1987 Sep;65(9):790-7. doi: 10.1139/o87-103.
This laboratory previously reported that a major 30 kilodalton (kDa) protein of the soluble cytoplasmic fraction of the rat slow-twitch soleus muscle is modulated by thyroid hormone. This protein has been purified and a portion of the primary structure has been determined. The sequence analysis suggested that the 30-kDa protein is carbonic anhydrase III (CA III; EC 4.2.1.1). The reaction of the protein with a CA III specific antibody and the similar modulation of CA III by thyroid hormone also support this conclusion. Immunochemical quantification of CA III and measurement of CA activity were performed in skeletal muscles of defined fiber-type composition from rats that were rendered hyperthyroid by treatment with 3,3',5-triiodo-L-thyronine. These experiments revealed that CA activity and CA III content are deinduced in the soleus muscle (primarily type I fibers) and induced in the superficial vastus lateralis muscle (primarily type IIb), whereas no changes were detected in the tibialis anterior muscle (primary type IIa). These results show that the modulation of CA III by thyroid hormone in rat skeletal muscle is not limited to the slow-twitch soleus muscle and that the amplitude and direction of this modulation are directly related to the initial fiber-type composition of the skeletal muscle.
本实验室先前报道，大鼠慢肌比目鱼肌可溶性细胞质部分的一种主要的30千道尔顿（kDa）蛋白质受甲状腺激素调节。该蛋白质已被纯化，并且已确定了部分一级结构。序列分析表明，30 kDa蛋白质是碳酸酐酶III（CA III；EC 4.2.1.1）。该蛋白质与CA III特异性抗体的反应以及甲状腺激素对CA III的类似调节也支持这一结论。在用3,3',5-三碘-L-甲状腺原氨酸处理使大鼠甲状腺功能亢进后，对具有明确纤维类型组成的大鼠骨骼肌进行了CA III的免疫化学定量和CA活性的测定。这些实验表明，比目鱼肌（主要是I型纤维）中的CA活性和CA III含量降低，而股外侧肌浅层（主要是IIb型）中的CA活性和CA III含量升高，而胫骨前肌（主要是IIa型）中未检测到变化。这些结果表明，甲状腺激素对大鼠骨骼肌中CA III的调节不仅限于慢肌比目鱼肌，而且这种调节的幅度和方向与骨骼肌的初始纤维类型组成直接相关。
