Biomaterial Database

The 5'-termini of heterogeneous nuclear RNA: a comparison among molecules of different sizes and ages. 1977

U Schibler, and R P Perry

The composition of the 5' polyphosphorylated and capped termini of pulse labeled hnRNA from mouse L cells was analyzed by two-dimensional electrophoresis. Purine tri- and diphosphates: pppG, pppA, ppG and ppA; as well as four varieties of cap structure: m7GpppXm, Xm = Gm, (m6) Am, Cm and Um, were detected. With increasing labeling time the relative proportion of hnRNA molecules with tri- and diphosphorylated 5' ends decreases and the relative proportion of capped hnRNA increases, indicating that caps are metabolically more stable than the polyphosphate termini. About half of the hnRNA molecules that are labeled within 2 hr have capped ends. This finding, together with results of earlier kinetic and structural studies, implies that a relatively high proportion of the labeled hnRNA molecules are mRNA precursors. Large hnRNA molecules exhibit a higher proportion of capped ends and a lower proportion of 5'-triphosphate ends as compared to small hnRNA. Given the lower stability of triphosphate termini relative to caps, this result may mean that capping of some hnRNA molecules can occur before the completion of transcription.

UI	MeSH Term	Description	Entries
D007739	L Cells	A cultured line of C3H mouse FIBROBLASTS that do not adhere to one another and do not express CADHERINS.	Earle's Strain L Cells,L Cell Line,L Cells (Cell Line),L-Cell Line,L-Cells,L-Cells, Cell Line,L929 Cell Line,L929 Cells,NCTC Clone 929 Cells,NCTC Clone 929 of Strain L Cells,Strain L Cells,Cell Line L-Cell,Cell Line L-Cells,Cell Line, L,Cell Line, L929,Cell Lines, L,Cell, L,Cell, L (Cell Line),Cell, L929,Cell, Strain L,Cells, L,Cells, L (Cell Line),Cells, L929,Cells, Strain L,L Cell,L Cell (Cell Line),L Cell Lines,L Cell, Strain,L Cells, Cell Line,L Cells, Strain,L-Cell,L-Cell Lines,L-Cell, Cell Line,L929 Cell,Strain L Cell
D008970	Molecular Weight	The sum of the weight of all the atoms in a molecule.	Molecular Weights,Weight, Molecular,Weights, Molecular
D009843	Oligoribonucleotides	A group of ribonucleotides (up to 12) in which the phosphate residues of each ribonucleotide act as bridges in forming diester linkages between the ribose moieties.
D002467	Cell Nucleus	Within a eukaryotic cell, a membrane-limited body which contains chromosomes and one or more nucleoli (CELL NUCLEOLUS). The nuclear membrane consists of a double unit-type membrane which is perforated by a number of pores; the outermost membrane is continuous with the ENDOPLASMIC RETICULUM. A cell may contain more than one nucleus. (From Singleton & Sainsbury, Dictionary of Microbiology and Molecular Biology, 2d ed)	Cell Nuclei,Nuclei, Cell,Nucleus, Cell
D001483	Base Sequence	The sequence of PURINES and PYRIMIDINES in nucleic acids and polynucleotides. It is also called nucleotide sequence.	DNA Sequence,Nucleotide Sequence,RNA Sequence,DNA Sequences,Base Sequences,Nucleotide Sequences,RNA Sequences,Sequence, Base,Sequence, DNA,Sequence, Nucleotide,Sequence, RNA,Sequences, Base,Sequences, DNA,Sequences, Nucleotide,Sequences, RNA
D012265	Ribonucleotides	Nucleotides in which the purine or pyrimidine base is combined with ribose. (Dorland, 28th ed)	Ribonucleoside Phosphates,Ribonucleotide,Phosphates, Ribonucleoside
D012313	RNA	A polynucleotide consisting essentially of chains with a repeating backbone of phosphate and ribose units to which nitrogenous bases are attached. RNA is unique among biological macromolecules in that it can encode genetic information, serve as an abundant structural component of cells, and also possesses catalytic activity. (Rieger et al., Glossary of Genetics: Classical and Molecular, 5th ed)	RNA, Non-Polyadenylated,Ribonucleic Acid,Gene Products, RNA,Non-Polyadenylated RNA,Acid, Ribonucleic,Non Polyadenylated RNA,RNA Gene Products,RNA, Non Polyadenylated