HeLa cell DNA polymerase alpha is tightly associated with tryptophanyl-tRNA synthetase and diadenosine 5',5"'-P1,P4-tetraphosphate binding activities.

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Abstract
The purified high MW-form of HeLa [human cervical cancer] cell DNA polymerase .alpha. (deoxynucleosidetriphosphate:DNA deoxynucleotidyltransferase, EC 2.7.7.7) associated tightly with several aminoacetyl-tRNA synthetase activities. Fractionation of the high-MW enzyme on hexylagarose followed by gel filtration, chromatography on phosphocellulose or polyacrylamide gel electrophoresis under nondenaturing conditions demonstrated copurification of only tryptophanyl-tRNA synthetase [L-tryptophan:tRNATrp ligase (AMP-forming), EC 6.1.1.2] along with DNA polymerase .alpha.. The high- (660,000) and low-MW (145,000) forms of DNA polymerase .alpha. possessed a highly specific, noncovalent, diadenosine 5'',5''''''-P1,P4-tetraphosphate (Ap4A) binding activity. The Kd were determined to be 16 and 22 .mu.M, respectively, by use of a charcoal adsorption procedure. No high-affinity binding of ATP could be detected. These findings suggest a link between the amino acid activation process and DNA replication in mammalian cells.