Molecular cloning of the p45 subunit of pyruvate dehydrogenase kinase
Purified preparations of rat heart pyruvate dehydrogenase kinase have two polypeptides with molecular weights of 48,000 (p48) and 45,000 (p45). Recently, we reported the primary structure of p48 (Popov, K. M., Kedishvili, N. Y., Zhao, Y., Shimomura, Y., Crabb, D. W., and Harris, R. A. (1993) J. Biol...
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Published in | The Journal of biological chemistry Vol. 269; no. 47; pp. 29720 - 29724 |
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Main Authors | , , , , |
Format | Journal Article |
Language | English |
Published |
United States
American Society for Biochemistry and Molecular Biology
25.11.1994
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Subjects | |
Online Access | Get full text |
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Summary: | Purified preparations of rat heart pyruvate dehydrogenase kinase have two polypeptides with molecular weights of 48,000 (p48)
and 45,000 (p45). Recently, we reported the primary structure of p48 (Popov, K. M., Kedishvili, N. Y., Zhao, Y., Shimomura,
Y., Crabb, D. W., and Harris, R. A. (1993) J. Biol. Chem. 268, 26602-26606) and presented evidence that (i) it exhibits kinase
activity for pyruvate dehydrogenase and (ii) it belongs to a family of mitochondrial protein kinases unique from other eukaryotic
protein kinases. Here, we report the molecular cloning and deduced amino acid sequence of p45. The protein sequence of p45
has 70% identity to the protein sequence of p48. Minor differences exist throughout the protein sequences with the greatest
difference occurring at the amino termini. Recombinant p45 protein, expressed in Escherichia coli and purified to homogeneity,
catalyzed the phosphorylation and inactivation of kinase-depleted pyruvate dehydrogenase complex, indicating that p45 and
p48 correspond to different isoforms of pyruvate dehydrogenase kinase. Northern blot analysis revealed a single hybridizing
species of 2.5 kilobases. The highest level of p45 message expression was found in heart and skeletal muscle and the lowest
in spleen and lung. Liver, kidney, brain, and testis express intermediate amounts of p45 mRNA. In contrast, p48 mRNA is predominantly
expressed in heart, with other tissues expressing only a modest amount of this message. Tissue-specific expression of isoforms
of pyruvate dehydrogenase kinase may indicate the existence of tissue-specific mechanisms for the regulation of pyruvate dehydrogenase
activity. |
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Bibliography: | ObjectType-Article-2 SourceType-Scholarly Journals-1 ObjectType-Feature-1 content type line 23 |
ISSN: | 0021-9258 1083-351X |
DOI: | 10.1016/S0021-9258(18)43940-3 |