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Abstract
Other workers have reported that vesicular stomatitis virus makes aberrantly long polyadenylic acid [poly(A)] tracts in the presence of S-adenosylhomocysteine (S-Ado-Hcy). In the work reported in this paper, the effects of various analogues of S-adenosylmethionine (S-Ado-Met) and ATP on polyadenylation in an in vitro transcription system were examined to determine whether S-Ado-Hcy exerted its effect on polyadenylation due to its relationship to S-Ado-Met or to ATP. It appeared that compounds which affected polyadenylation were those which were closely related to S-Ado-Met and that had the same L-aminoacyl side chain [(COOH)–CH(NH)2–CH2–CH2–]; the nature of the substituent at the –S+(CH3)– position of S-Ado-Met was less important. These analogues appeared to compete with S-Ado-Met for a binding site(s). These data support a model whereby compounds binding at an S-Ado-Met-binding site may have allosteric effects by causing or preventing conformational changes which are involved in polyadenylation reactions, perhaps by affecting the rate of polyadenylation or of termination.
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