title: [Structure of nuclear pre-mRNA. XI. Triphosphorylated and blocked 5'-ends in the pre-mRNA].
abstract: The nature of the 5'-termini in pre-mRNA isolated from Ehrlich carcinoma cells has been investigated. To discriminate between triphosphorylated 5'-ends and capped structures different methods were used including treatment by alkaline phosphatase and several chromatographic methods. It was shown that heavey pre-mRNA contains a significant number of non-blocked triphosphorylated nucleotides at the 5'-end termini. However, phosphatase resistent, blocked 5'-termini were also found. 5'-terminal nucleotides in triphosphorylated pre-mRNA are G in a 3 : 2 ratio. In contrast to nuclear pre-mRNA cytoplasmic poly(A)+mRNA does not contain triphosphorylated 5'-ends but does contain the "cap" structure only. To elucidate the pre-mRNA topography the localization of homopolymeric regions of pre-mRNA, poly(A) and oligo(U), in relation to 5'terminal structures has been investigated. The experiments showed that the distance between 3'-terminal poly(A) sequences and 5'-end triphosphates is longer than 1500--2000 nucleotides. At the same time the distance between the latter and oligo(U) in pre-mRNA is much shorter.
mesh_terms: D000469:Alkaline Phosphatase; D000818:Animals; D002286:Carcinoma, Ehrlich Tumor / Q000032:analysis*; D002467:Cell Nucleus / Q000032:analysis*; D051379:Mice; D010766:Phosphorylation; D011061:Poly A / Q000032:analysis; D012333:RNA, Messenger; D012265:Ribonucleotides / Q000032:analysis
chemical_list: D012333:RNA, Messenger; D012265:Ribonucleotides; D011061:Poly A; D000469:Alkaline Phosphatase
vernacular_title: Struktura iadernoi pro-mRNK. XI. Trifosforilirovannye i blokirovannye 5'-kontsy v pro-mRNK.