Thibault M C, Havaranis A S, Heywood S M
Am J Physiol. 1981 Nov;241(5):C269-72. doi: 10.1152/ajpcell.1981.241.5.C269.
Myosin heavy chain (MHC) synthesis in cultures from chick pectoralis muscle cells was determined by [35S]methionine incorporation. Two types of MHC, migrating as 200,000-dalton components on sodium dodecyl sulfate polyacrylamide gels, were distinguished with antibodies against adult fast and slow MHC. Their synthesis was revealed by autoradiography. The effect of a sciatic nerve extract on the synthesis of the two types of MHC was also determined. Control experiments show that fast MHC is primarily synthesized in 48-h cultures. At a later stage of development (5- to 7-day cultures), slow MHC is also produced. The nerve extract promotes muscle cell differentiation and stimulates the synthesis of the slow type of MHC at an earlier stage of development (i.e., at 48 h as compared with 5-7 day in controlled cultures). It is concluded therefore that presumptive fast muscle cells in culture synthesize initially fast MHC and later both types of MHC (slow and fast). These results also suggest that the sciatic nerve extract is capable either of activating the transcription of the structural gene for slow MHC or of activating the translation of preexisting messenger RNA coding for this protein.
通过[35S]甲硫氨酸掺入法测定了鸡胸肌细胞培养物中肌球蛋白重链（MHC）的合成。在十二烷基硫酸钠聚丙烯酰胺凝胶上以200,000道尔顿组分迁移的两种类型的MHC，用抗成年快肌和慢肌MHC的抗体进行了区分。它们的合成通过放射自显影显示。还测定了坐骨神经提取物对两种类型MHC合成的影响。对照实验表明，快肌MHC主要在48小时培养物中合成。在发育后期（5至7天培养物），也产生慢肌MHC。神经提取物促进肌肉细胞分化，并在发育早期（即与对照培养物中的5至7天相比，在48小时时）刺激慢肌型MHC的合成。因此得出结论，培养中的假定快肌细胞最初合成快肌MHC，后来合成两种类型的MHC（慢肌和快肌）。这些结果还表明，坐骨神经提取物能够激活慢肌MHC结构基因的转录，或者激活编码该蛋白的预先存在的信使RNA的翻译。
