Search PubMed⌕ Search

Biomedical subjects

R P Perry

Publications and source records attributed to R P Perry.

At least 109 records · Page 6Linked to original sources
PubMed1976

Kinetics of formation of 5' terminal caps in mRNA.

A kinetic analysis of the labeling of the methylated components of messenger RNA and heterogeneous nuclear RNA in mouse L cells indicates that the 5' terminal cap I structures (m7GpppXmpYp) of mRNA are derived from 5' terminal cap structures of hnRNA. Most of the hnRNA caps are conserved during processing, whereas only a portion of the internal m6A residues in hnRNA are conserved. The cap II structures (m7GpppXmpYmpZp), which constitute the 5' termini of some mRNAs, arise by a "secondary" methylation that occurs after the mRNAs have entered the cytoplasm. This secondary methylation is apparently restricted to a particular subclass of mRNAs having a high frequency of pyrimidine nucleotides at position Y, a composition at position X which differs from that of the bulk of the cap I-terminated mRNAs, and a relatively slow rate of turnover.

Kinetics↗
PubMed1975

Methylated constituents of heterogeneous nuclear RNA: presence in blocked 5' terminal structures.

A substantial portion of the hnRNA of mouse L cells contains internal residues of N6-methyl adenylate and blocked 5' terminal sequences which are apparently of the type m7G5' ppp5' YmpZp..., in which 7-methyl guanosine is joined by a 5'-5' pyrophosphate linkage to a 2'-0-methylated residue, Ym. These sequences are indistinguishable from those comprising one of the two classes of blocked 5' sequences found in mRNA, and are quite distinct from those comprising the other class. The remarkable similarity in 5' terminal methylated sequences of hnRNA and a major fraction of mRNA appears to extend even to the relative occurrence of each of the four 2'-0-methylated species in position Ym.

Base Sequence↗
PubMed1975

The methylated constituents of L cell messenger RNA: evidence for an unusual cluster at the 5' terminus.

An analysis of the methylated constituents of L cell mRNA by a combination of chromatographic methods and enzymatic treatments indicates that they comprise both 2'-O-methyl nucleosides and N6-methyl adenine, and/or 1-methyl adenine, and suggests that the 2'-O-methyl nucleotides, Ym, are part of an unusual class of sequences forming the 5' terminus of mRNA. These sequences seem to contain two 2'-O-methyl residues and a terminal residue that is not phosphorylated but, nevertheless, is blocked with respect to polynucleotid kinase reactivity. A strong candidate is a sequence of the type XppY1mpY2mpZp..., where X represents a blocking group which is itself occasionally methylated. The sequences isolated from total poly(A)+ mRNA contain all four species of 2'-O-methylated nucleoside, indicating some variability among different mRNA species. The methylated sequences do not appear to be enriched in the mRNA which hybridizes with repetitive DNA. The average L cell mRNA molecule also contains three residues of N6-methyl adenine. These residues are not part of the poly(A) segment, but appear to be located internal to the poly(A) near the 3' end of the mRNA molecules.

Adenine↗