order of addition experiments are used to show that the binding of lac repressor to the operator is competitive with that of the rna polymerase ( nucleosidetriphosphate : rna nucleotidyltransferase , ec 2.7.7.6 ) to the promoter , thus demonstrating functional overlap of the operator and promoter sites .
C0035681
rna polymerase
C0035673
rna nucleotidyltransferase