title: Biological, biochemical, and physicochemical evidence for the existence of the polyadenylic-polyuridylic-polyinosinic acid triplex.
abstract: When primary rabbit kidney cell cultures are treated with either polyadenylic acid-polyuridylic acid or polyadenylic acid-polyribothymidylic acid (poly(rT)) and then judiciously exposed to actinomycin D and cycloheximide, high titers of interferon are found in the extracellular medium ("superinduction") (Vilcek, J. (1970) Ann. N. Y. Acad. Sci. 173, 390-403; Tan, Y. H., Armstrong, J. A., Ke, Y. H., and Ho, M. (1970) Proc. Natl. Acad.  Sci. U. S. A. 67, 464-471). If polyinosinic acid is added 1 hour prior to, simultaneously with, or 1 hour after the active interferon inducers, dramatic reductions in interferon production from the "superinduced" cells result. Based on experiments involving sucrose gradient ultracentrifugation, pancreatic ribonuclease A resistance, ultraviolet mixing curves, and ultraviolet absorbance-temperature profiles, the explanation for this phenomenon was determined to be the formation of polynucleotide triplexes in the following way: poly(A)-poly(U) + poly(I) yields poly(A)-poly(U)-poly(I)poly(A)-poly(rT) + poly(I) yields poly(A)-poly(rT)-poly(I). In addition, based on similar methodology, the following reactions involving these triplexes were demonstrated: poly(A)-2 poly(I) + poly(U) yields poly(A)-poly(U)-poly(I) + poly(I)poly(A)-2 poly(I) + poly(rT) yields poly(A)-poly(rT)-poly(I) + poly(I)POLY(A)-2 poly(I) + 2 poly(U) yields poly(A)-2 poly(U) + 2 poly(I) and POLY(A)-poly(U)-poly(I) + poly (U) yields poly(A)-2 poly(U) + poly(I).
mesh_terms: D000227:Adenine Nucleotides; D000818:Animals; D001665:Binding Sites; D002478:Cells, Cultured; D002499:Centrifugation, Density Gradient; D003513:Cycloheximide / Q000494:pharmacology; D003609:Dactinomycin / Q000494:pharmacology; D007292:Inosine Nucleotides; D007369:Interferon Inducers / Q000494:pharmacology*; D007668:Kidney / Q000187:drug effects / Q000378:metabolism*; D007700:Kinetics; D009690:Nucleic Acid Conformation; D009691:Nucleic Acid Denaturation; D009994:Osmolar Concentration; D010179:Pancreas / Q000201:enzymology; D011063:Poly A-U / Q000494:pharmacology; D011072:Poly U / Q000494:pharmacology*; D011119:Polynucleotides / Q000494:pharmacology*; D011817:Rabbits; D012260:Ribonucleases; D013056:Spectrophotometry, Ultraviolet; D013696:Temperature; D013942:Thymine Nucleotides
chemical_list: D000227:Adenine Nucleotides; D007292:Inosine Nucleotides; D007369:Interferon Inducers; D011119:Polynucleotides; D013942:Thymine Nucleotides; D003609:Dactinomycin; D011063:Poly A-U; D011072:Poly U; D003513:Cycloheximide; D012260:Ribonucleases