Pyruvate Dehydrogenase Phosphatase Regulatory Subunit, Mitochondrial (PDPR)

cDNA encoding the regulatory subunit of bovine PDPr has been cloned. Overlapping cDNA fragments were generated by the polymerase chain reaction from bovine genomic DNA and from cDNA synthesized from bovine poly(A)+ RNA and total RNA. The mature form of PDPr was expressed in Escherichia coli as a maltose-binding protein fusion, and the recombinant protein was purified to near homogeneity. It exhibited properties characteristic of the native PDPr, including recognition by antibodies against native bovine PDPr, ability to decrease the sensitivity of the catalytic subunit to Mg2+, and reversal of this inhibitory effect by the polyamine spermine. A BLAST search of protein data bases revealed that PDPr is distantly related to the mitochondrial flavoprotein dimethylglycine dehydrogenase, which functions in choline degradation.