ISOLATION OF THE MYC TRANSCRIPTION FACTOR NUCLEOSIDE DIPHOSPHATE KINASE AND THE MULTIFUNCTIONAL ENZYME GLYCERALDEHYDE-3-PHOSPHATE DEHYDROGENASE BY CAMP AFFINITY-CHROMATOGRAPHY

Cyclic AMP affinity chromatography applied to various mammalian tissue extracts yielded two proteins in addition to the regulatory subunits of protein kinase. This paper characterizes these proteins and provide s a simple procedure for their preparation. The polypeptides (36 kDa a nd a 19 kDa/21 kDa doublet) were isolated from the cAMP matrix by sequ ential elution with cAMP solutions of increasing concentrations. Micro sequencing was accomplished following chemical or enzymic degradation of isolated polypeptides. Partial amino acid sequences of the 36 kDa p rotein and analyses of its enzymic activity indicated identity with gl yceraldehyde-3-phosphate dehydrogenase whilst the lower MW protein pro ved to be identical with mammalian nucleoside diphosphate kinase subun its. In both cases, binding to cAMP appeared to occur at the nucleotid e (NAD and ATP, respectively) sites. In conclusion, we present a one s tep-procedure, applicable to tissue and cell extracts, which allows th e simultaneous isolation of both glyceraldehyde-3-phosphate dehydrogen ase and nucleoside diphosphate kinase. This procedure may help to eluc idate the multiple functions of these two important enzymes.