the macromolecules contacted by the leading ( 5 ' ) end of the growing rna chain in the transcription complex have been determined previously by photoaffinity labeling experiments using aryl azides attached to the leading end of nascent rna [ hanna , m. m. , & meares , c. f. ( 1983 ) proc . natl . acad . sci . u.s.a. 80 , 4238-4242 ] .
C0040649
transcription
C0035668
rna