Bataille N, Schmitt N, Aumercier-Maes P, Ollivier B, Lucas-Heron B, Lestienne P
U 298 INSERM, CHR Angers, France.
Biochem Biophys Res Commun. 1994 Sep 30;203(3):1477-82. doi: 10.1006/bbrc.1994.2351.
The cDNA of a mitochondrial calcium binding protein, "calmitine", has been cloned from a human skeletal muscle cDNA library. One cDNA of 1.8 kb has been isolated and sequenced. It encodes for a protein of 390 amino acid residues of 41,746 KDa and contains a leading peptide of 28 amino acids. The sequencing showed the possibility for 21 phosphorylation sites, 4 myristylation sites, and one N glycosylation site. Sequence comparison with other proteins revealed the identity of calmitine with calsequestrine, the sarcoplasmic reticulum low affinity, but high Ca2+ binding capacity, protein isolated in 1971. Subcellular fractionation showed a marked increase in these Ca2+ binding proteins in mitochondria as compared with the sarcoplasmic reticulum; furthermore the mitochondrial matrix is highly enriched with that protein. Therefore, our data either suggest a bicompartimentation of calmitine or indicate that the localization of calsequestrine should be reconsidered in the light of our data. Calmitine represents the Ca2+ reservoir of mitochondria, the function of which could be similar to what has been reported for calsequestrine in the sarcoplasmic reticulum.
一种线粒体钙结合蛋白“钙肌宁”的互补脱氧核糖核酸（cDNA）已从人骨骼肌cDNA文库中克隆出来。一个1.8千碱基对（kb）的cDNA已被分离并测序。它编码一种由390个氨基酸残基组成、分子量为41,746道尔顿（KDa）的蛋白质，并且含有一个由28个氨基酸组成的前导肽。测序显示该蛋白可能有21个磷酸化位点、4个豆蔻酰化位点和1个N-糖基化位点。与其他蛋白质的序列比较揭示了钙肌宁与1971年分离出的肌质网低亲和力但高钙离子结合能力的蛋白——肌集钙蛋白的一致性。亚细胞分级分离显示，与肌质网相比，线粒体中这些钙离子结合蛋白显著增加；此外，线粒体基质中该蛋白高度富集。因此，我们的数据要么提示钙肌宁存在双区室化，要么表明应根据我们的数据重新考虑肌集钙蛋白的定位。钙肌宁代表线粒体的钙离子储存库，其功能可能与肌质网中肌集钙蛋白的功能类似。
