Technikova-Dobrova Z, Sardanelli A M, Speranza F, Scacco S, Signorile A, Lorusso V, Papa S
Department of Medical Biochemistry and Biology, University of Bari, Piazza G.Cesare 70124 Bari, Italy.
Biochemistry. 2001 Nov 20;40(46):13941-7. doi: 10.1021/bi011066p.
A study is presented on cyclic adenosine monophosphate- (cAMP-) dependent phosphorylation of mammalian mitochondrial proteins. Immunodetection with specific antibodies reveals the presence of the catalytic and the regulatory subunits of cAMP-dependent protein kinase (PKA) in the inner membrane and matrix of bovine heart mitochondria. The mitochondrial cAMP-dependent protein kinase phosphorylates mitochondrial proteins of 29, 18, and 6.5 kDa. With added histone as substrate, PKA exhibits affinities for ATP and cAMP and pH optimum comparable to those of the cytosolic PKA. Among the mitochondrial proteins phosphorylated by PKA, one is the nuclear-encoded (NDUFS4 gene) 18 kDa subunit of complex I, which has phosphorylation consensus sites in the C terminus and in the presequence. cAMP promotes phosphorylation of the 18 kDa subunit of complex I in myoblasts in culture and in their isolated mitoplast fraction. In both cases cAMP-dependent phosphorylation of the 18 kDa subunit of complex I is accompanied by enhancement of the activity of the complex. These results, and the finding of mutations in the NDUFS4 gene in patients with complex I deficiency, provide evidence showing that cAMP-dependent phosphorylation of the 18 kDa subunit of complex I plays a major role in the control of the mitochondrial respiratory activity.
本文介绍了一项关于哺乳动物线粒体蛋白的环磷酸腺苷（cAMP）依赖性磷酸化的研究。用特异性抗体进行免疫检测发现，牛心脏线粒体的内膜和基质中存在cAMP依赖性蛋白激酶（PKA）的催化亚基和调节亚基。线粒体cAMP依赖性蛋白激酶可使分子量为29 kDa、18 kDa和6.5 kDa的线粒体蛋白发生磷酸化。以添加的组蛋白为底物时，PKA对ATP和cAMP的亲和力以及pH最佳值与胞质PKA相当。在PKA磷酸化的线粒体蛋白中，有一种是复合物I的核编码（NDUFS4基因）18 kDa亚基，其在C末端和前序列中有磷酸化共有位点。cAMP可促进培养的成肌细胞及其分离的线粒体片段中复合物I的18 kDa亚基的磷酸化。在这两种情况下，复合物I的18 kDa亚基的cAMP依赖性磷酸化都伴随着复合物活性的增强。这些结果，以及在复合物I缺乏症患者的NDUFS4基因中发现的突变，提供了证据表明复合物I的18 kDa亚基的cAMP依赖性磷酸化在控制线粒体呼吸活性中起主要作用。
