title: Structural transitions in polyadenylic acid and hypothesis on biological role of its double-stranded forms.
abstract: Under various conditions poly(A) exists in different forms such as single-stranded helix, two double-helical forms and others. The formation of double-stranded helices is induced by adenine protonation. Under physiological ionic strengths they are formed at acidic pH, but under the same conditions methylated poly(A) has double-stranded structure at alkaline pH. Since the shift of adenine protonation pKa to alkaline region may be caused not only by chemical modification of poly(A) but also its interaction with proteins, it is quite probable that double oligo(A)-helices are formed in the living cell as well. In this article the hypothesis on possible biological role of poly(A) double-stranded forms has been discussed in details. The models of involvement of double oligo(A)-sequences of RNA in such intracellular processes as termination of mRNA poly(A) tails synthesis and autoregulation of poly(A)-binding protein synthesis are suggested as an example.
authors.affiliation: Institute of Molecular Biology and Genetics of National Academy of Sciences of Ukraine, Kyiv.
authors.forename: M I
authors.initials: MI
authors.lastname: Zarudnaya
authors.forename: D M
authors.initials: DM
authors.lastname: Hovorun
mesh_terms: D009690:Nucleic Acid Conformation; D011061:Poly A / Q000737:chemistry* / Q000378:metabolism; D012330:RNA, Double-Stranded / Q000737:chemistry* / Q000502:physiology
chemical_list: D012330:RNA, Double-Stranded; D011061:Poly A