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标题：Bovine heart fructose-6-phosphate 2-kinase/fructose-2,6-bisphosphatase: complete amino acid sequence and localization of phosphorylation sites
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作者：J Sakata ; K Uyeda
期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：1990
卷号：87
期号：13
页码：4951-4955
DOI：10.1073/pnas.87.13.4951
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：We have shown previously that bovine heart fructose-6-phosphate 2-kinase/fructose-2,6-bisphosphatase (EC 2.7.1.105 /3.1.3.46) is phosphorylated by cAMP-dependent protein kinase and protein kinase C; phosphorylation results in activation of kinase. This activation of heart enzyme is in contrast to results with the liver isozyme, in which phosphorylation by cAMP-dependent protein kinase inhibits the kinase activity. As an initial step toward understanding this difference between the isozymes we have determined the DNA sequence of the heart enzyme and analyzed the amino acid sequence with special emphasis on the location of the phosphorylation site. We isolated and sequenced two overlapping cDNA fragments, which together could encode the complete amino acid sequence of bovine heart fructose-6-phosphate 2-kinase/fructose-2,6-bisphosphatase, a protein of 530 amino acids, with a calculated molecular weight of 60,679. Since the deduced protein contained amino acid sequences identical to the sequences of four known tryptic peptides from this enzyme we concluded that the deduced protein sequence did represent bovine heart enzyme. In addition, a cDNA fragment hybridized to a 4-kilobase mRNA from bovine heart. The phosphorylation sites of the heart enzyme were located near the C terminus, whereas the phosphorylation site of the liver isozyme is known to be located near the N terminus. These opposite locations of the phosphorylation sites may explain the contrasting effect of the covalent modification on the enzymes' activities.