title: Initiation specificity of the poly(cytidylic acid)-dependent Qbeta replicase activity.
abstract: The initiation specificity of RNA synthesis catalysed by the poly(C)-dependent Qbeta replicase activity was investigated with various synthetic ribopolymers as template. It was found that the initiation efficiency of a series of oligo(C) with various chain lengths is proportional to the template size. Synthetic riboheteropolymers containing cytidylic acid were accepted as templates only if they contained at their 3' end a cytidylic acid sequence of more than 5 nucleotides. Such an oligocytidylate sequence served also as an initiator sequence for copying the non-cytidylic-acid-containing part of the heterotemplate. RNA synthesis always began with the incorporation of GTP, even if the 3'-terminating nucleotide of the template was not cytidylic acid.
mesh_terms: D001483:Base Sequence; D004926:Escherichia coli / Q000201:enzymology; D008970:Molecular Weight; D009841:Oligonucleotides / Q000494:pharmacology; D011066:Poly C / Q000494:pharmacology*; D011131:Polyribonucleotides / Q000494:pharmacology*; D011777:Q beta Replicase / Q000378:metabolism*; D012316:RNA Nucleotidyltransferases / Q000378:metabolism*; D013329:Structure-Activity Relationship
chemical_list: D009841:Oligonucleotides; D011131:Polyribonucleotides; D011066:Poly C; D011777:Q beta Replicase; D012316:RNA Nucleotidyltransferases