Matsuda R, Bandman E, Strohman R C
Differentiation. 1982;23(1):36-42. doi: 10.1111/j.1432-0436.1982.tb01265.x.
The two myosin isozymes (SM1 and SM2) of the anterior latissimus dorsi muscle of the chicken change in relative concentration during development. As SM1 decreases from 13 days of embryonic growth through 1 year of adult maturation, SM2 increases. In the adult muscle SM2 accounts for over 95% of the total myosin. The myosin heavy chains of the two isozymes are distinctly different and may be separated from each other by 5% SDS polyacrylamide gel electrophoresis. The faster migrating myosin heavy chain is identified as originating from SM1 and the slower migrating myosin heavy chain from SM2 myosin isozymes. The myosin heavy chains change in relative concentration during development exactly parallel with changes in SM1 and SM2 isozyme levels. Peptide map analysis also reveals that SM1 myosin heavy chains and SM2 myosin heavy chains are distinctly different. When RNA from the ALD muscle is added to reticulocyte lysate protein synthesizing systems the translation products are shown to include both SM1 and SM2 myosin heavy chains. These comigrate exactly on 5% SDS polyacrylamide gels with authentic counterparts from ALD muscle. Finally, when peptide maps of SM1 and SM2 myosin heavy chains synthesized in the reticulocyte lysate are compared they are again found to be distinctly different and each is identical to a peptide map of respective authentic SM1 and SM2 myosin heavy chains. It is concluded that the myosin heavy chains of SM1 and SM2 myosin isozymes of ALD muscle have different primary structures and that they are encoded by two distinctly different mRNAs.
鸡背阔肌的两种肌球蛋白同工酶（SM1和SM2）在发育过程中相对浓度发生变化。从胚胎发育13天到成年成熟1年，SM1浓度降低，而SM2浓度升高。在成年肌肉中，SM2占总肌球蛋白的95%以上。两种同工酶的肌球蛋白重链明显不同，可通过5%十二烷基硫酸钠聚丙烯酰胺凝胶电泳彼此分离。迁移速度较快的肌球蛋白重链来自SM1，迁移速度较慢的肌球蛋白重链来自SM2肌球蛋白同工酶。发育过程中肌球蛋白重链相对浓度的变化与SM1和SM2同工酶水平的变化完全平行。肽图分析也表明，SM1肌球蛋白重链和SM2肌球蛋白重链明显不同。当将来自背阔肌的RNA添加到网织红细胞裂解物蛋白质合成系统中时，翻译产物显示同时包含SM1和SM2肌球蛋白重链。它们在5%十二烷基硫酸钠聚丙烯酰胺凝胶上与来自背阔肌的真实对应物完全共迁移。最后，当比较在网织红细胞裂解物中合成的SM1和SM2肌球蛋白重链的肽图时，发现它们再次明显不同，且各自与相应的真实SM1和SM2肌球蛋白重链的肽图相同。得出的结论是，背阔肌SM1和SM2肌球蛋白同工酶的肌球蛋白重链具有不同的一级结构，且它们由两种明显不同的mRNA编码。
