Nucleic Acids Research, 1977, Vol. 4, No. 11 4007-4014
© 1977
Articles |
Modification of human DNA-dependent RNA polymerase activity by cyclic GMP
Sloan-Kettering Institute for Cancer Research 1250 First Avenue, New York, NY 10021, USA
Received September 8, 1977. The effect of low concentrations of cyclic GMP (guanosine 3':5'- cyclic monophosphate) on the in vitro enzymatic activities of DNA-dependent RNA polymerases isolated from human peripheral blood lymphocytes has been investigated. In agreement with earlier studies which employed isolated nuclei as the enzyme source, an increase in the activity of partially purified RNA polymerase I is observed in the presence of cyclic GMP (108 to 1010M). RNA polymerase II activity is inhibited by the presence of cyclic GMP at concentrations between 108 and 1010M RNA polymerase III activity is stimulated in a bimodal fashion by the presence of cyclic GMP with maximal activity noted at 108 to 1010M and 105M In addition, [3H] cyclic GMP binds specifically to chromatographic fractions which are known to contain RNA polymerases I, II and III. This binding to RNA polymerases II and III is apparently less tenacious as demonstrated by dissociation studies. The observations provide additional evidence for a role for cyclic GMP in the regulation of RNA synthesis.