Oe M, Ohnishi-Kameyama M, Nakajima I, Muroya S, Chikuni K
National Institute of Livestock and Grassland Science, Tsukuba, Ibaraki 305-0901, Japan.
Meat Sci. 2007 Apr;75(4):558-63. doi: 10.1016/j.meatsci.2006.09.003. Epub 2006 Oct 25.
Nucleotide sequences encoding an entire coding region for bovine tropomyosin (TPM) isoforms were determined. Three TPM isoforms, TPM1, TPM2 and TPM3, were expressed in bovine skeletal muscles, and exhibited a 93.3%, 99.6% and 100% amino acid homology to the human sequence, respectively. Based on the sequences, the composition of TPM isoforms was analyzed on cDNA and protein levels from five physiologically different muscles (masseter, diaphragm, psoas major, longissimus thoracis and semitendinosus) using RT-PCR and proteome analyses. Although the content of TPM2 was constantly about 50% of the total TPM in all muscles, the contents of TPM1 and TPM3 were different in muscles according to their function in muscle contraction. In masseter, the content of TPM3 cDNA was about 50% and higher than that of other muscles. In longissimus thoracis and semitendinosus, the contents of TPM1 cDNA were 29.6% and 31.7%, respectively, which were comparatively higher than that of other muscles. The result suggests that the TPM dimer consists of the TPM2 subunit regularly and TPM1 or TPM3 depending on whether the muscle is fast or slow type, respectively.
确定了编码牛原肌球蛋白（TPM）亚型完整编码区的核苷酸序列。三种TPM亚型，即TPM1、TPM2和TPM3，在牛骨骼肌中表达，并且与人类序列的氨基酸同源性分别为93.3%、99.6%和100%。基于这些序列，使用逆转录聚合酶链反应（RT-PCR）和蛋白质组分析，从五种生理功能不同的肌肉（咬肌、膈肌、腰大肌、胸最长肌和半腱肌）的cDNA和蛋白质水平分析了TPM亚型的组成。尽管TPM2的含量在所有肌肉中均恒定约占总TPM的50%，但TPM1和TPM3的含量在不同肌肉中因其在肌肉收缩中的功能而有所不同。在咬肌中，TPM3 cDNA的含量约为50%，高于其他肌肉。在胸最长肌和半腱肌中，TPM1 cDNA的含量分别为29.6%和31.7%，相对高于其他肌肉。结果表明，TPM二聚体分别根据肌肉是快肌型还是慢肌型，由TPM2亚基以及TPM1或TPM3有规律地组成。
