The Protein Kinase Activity in HBcAg and the Proposed Nucleic Acid Binding Properties of Core Polypeptide
Protein phosphorylation has become an important post-translational modification vital to the regulation of intermediate metabolism, hormone activity, neurotransmission, gene expression and a variety of other cellular processes (513, 514). Phosphorylation occurs through the action of protein kinases, which are enzymes capable of catalyzing the transfer of the gamma-phosphate of ATP (or of other nucleoside triphosphates) to the hydroxyl groups of serine and threonine residues (513, 514). Although other chemical groups in proteins could be phos-phorylated (e.g., carboxy, amino or aromatic hydroxyl), their frequencies in normal cells are relatively low and their specific biological roles not firmly established. While many cellular protein kinases are characterized as being stimulated in the presence of cyclic nucleotides, a number of others are not stimulated any further under these circumstances (513, 514). Protein kinase activities copurifying with many viruses have almost uniformly been resistant to any further induction upon addition of cyclic nucleotides, indicating that these enzymes are probably cyclic nucleotide independent.
KeywordsHydrolysis Hepatitis Hydroxyl Leukemia Serine
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