Hayashi K, Kanda K, Kimizuka F, Kato I, Sobue K
Department of Neurochemistry and Neurophamacology, Osaka University Medical School, Japan.
Biochem Biophys Res Commun. 1989 Oct 16;164(1):503-11. doi: 10.1016/0006-291x(89)91748-8.
Recently, the two Mr forms of caldesmon (Mr's in the range of 120-150kDa and 70-80kDa as judged by SDS-PAGE) have been identified. h-Caldesman (high Mr 120-150kDa caldesmon) is predominantly expressed in smooth muscles, and l-caldesmon (low Mr 70-80kDa caldesmon) in non-muscle cells. In this paper, we report the nucleotide sequence of chick embryo gizzard h-caldesmon cDNA and its translation into amino acid sequence. This sequence predicts a protein of 771 amino acids with a Mr of 88,743. The central portion of this sequence is composed of a 10-fold repeat of conserved amino acid sequence containing 13-15 amino acids. Further, a recombinant protein produced in Escherichia coli containing the full-length h-caldesmon cDNA has been characterized. Although the Mr of h-caldesmon predicted from amino acid sequence is 88,743, native and recombinant proteins show the same mol. wt. with 150kDa as measured by SDS-PAGE. This discrepancy may be due to the acidic amino acid-rich sequences at the N-terminal and central portions. A recombinant protein produced in E. coli possesses calmodulin-, F-actin- and tropomyosin-binding abilities in common with the native h-caldesmon.
最近，已鉴定出两种钙调蛋白（caldesmon）的Mr形式（通过SDS-PAGE判断，Mr在120 - 150kDa和70 - 80kDa范围内）。h-钙调蛋白（高Mr 120 - 150kDa钙调蛋白）主要在平滑肌中表达，而l-钙调蛋白（低Mr 70 - 80kDa钙调蛋白）在非肌肉细胞中表达。在本文中，我们报道了鸡胚砂囊h-钙调蛋白cDNA的核苷酸序列及其翻译成的氨基酸序列。该序列预测有一个由771个氨基酸组成、Mr为88,743的蛋白质。该序列的中央部分由一个含13 - 15个氨基酸的保守氨基酸序列的10倍重复组成。此外，对在大肠杆菌中产生的含有全长h-钙调蛋白cDNA的重组蛋白进行了表征。尽管从氨基酸序列预测的h-钙调蛋白的Mr为88,743，但天然蛋白和重组蛋白在SDS-PAGE测量中显示出相同的分子量，为150kDa。这种差异可能是由于N端和中央部分富含酸性氨基酸的序列。在大肠杆菌中产生的重组蛋白具有与天然h-钙调蛋白相同的钙调蛋白、F-肌动蛋白和原肌球蛋白结合能力。
