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Biomedical subjects

W Filipowicz

Publications and source records attributed to W Filipowicz.

103 records · Page 6Linked to original sources
PubMed1975

mRNA methylation and protein synthesis in extracts from embryos of brine shrimp, Artemia salina.

Cell-free protein-synthesizing extracts prepared from the brine shrimp, Artemia salina, translate methylated mRNAs. Reovirus unmethylated mRNA is inactive as a template when methylation is prevented by the inhibitor, S-adenosylhomocysteine. A salina mRNAs from both undeveloped and developed embryos contain 5'-terminal 7-methylguanosine in an inverted 5'-5' linkage through three phosphate groups to the rest of the polynucleotide chain. Removal of the 7-methylguanosine by beta elimination converts the mRNA from an active form to one inactive in protein synthesis in extracts of A. salina or wheat germ. Extracts of undeveloped and developed embryos methylate reovirus unmethylated mRNA at the 5' ends to form 5'-terminal structures of the type, m7G(5')ppp(5')G and m7G(5')ppp(5')Gm.

Animals↗
PubMed1975

Polypeptide chain initiation in eukaryotes: initiation factor MP in Artemia salina embryos.

The activity of IF-MP, a polypeptide chain initiation factor that forms a ternary complex with eukaryotic initiator Met-tRNA and GTP and promotes binding of the initiator to 40S ribosomes, is very low in undeveloped Artemia salina embryos but increases over 20-fold following resumption of development upon hydration of the cysts. The factor is present in both the ribosomal salt wash and high-speed-supernatant. Its specific activity is 50 times higher in the wash but its total activity is only about twice as high in the wash as in the supernatant. As is true of IF-MP from other eukaryotic sources, the A. salina factor is specific for eukaryotic Met-tRNAi and sensitive to SH-reagents, and its activity is GTP dependent.

Animals↗
PubMed1975

Preparation and characteristics of the structure of methoxyamine-modified f2 RNA.

Treatment of phage f2 RNA with [14-C]methoxyamine under non-denaturing conditions resulted in modification of exposed cytosines only. On methoxyamine treatment in the presence of 6 M-guanidine, all cytosines were modified. Under the conditions applied, no modification of adenine base in RNA chain occurred. The structure of modified f2 RNA preparations was studied by melting and sedimentation analysis. The ratio between the modification products (N-4-methoxycytosine and N-4-methoxy-6-methoxyamino-5,6-dihydrocytosine) was determined in RNA preparations modified under non-denaturing and denaturing conditions.

Binding Sites↗
PubMedDate not supplied

Formation of a 2'-phosphomonoester, 3',5'-phosphodiester linkage by a novel RNA ligase in wheat germ.

Extracts of wheat germ contain an RNA ligase activity that catalyses the conversation of linear polyribonucleotides into covalently closed circles. The newly formed 3',5'-phosphodiester bridge is resistant to alkali and a number of ribonucleases. This unusual stability is due to the presence of a phosphoryl group esterified to the 2'-position of the 3'-nucleotide joined. This is the first demonstration of an RNA ligase in higher plants and of a natural 2'-phosphomonoester, 3',5'-phosphodiester linkage.

Nucleic Acid Precursors↗
PubMedDate not supplied

[RNA in surface antigen of hepatitis B virus (HBsAg)].

RNA was isolated from HBsAg particles obtained by the method of preparatory immunoprecipitation with anti-HBs antibodies. RNA electrophoresis in polyacrylamide gel showed presence of one fraction with molecular weight about 28 000. The index of RNA sedimentation determined by the method of ultracentrifugation was about 4 S. RNA from HBsAg had no informative features of nucleic acids (m RNA) such as presence of methyl group 5' of the end sequence m7 GpppN ("cap"), translatory activity. It had also no features of tRNA since it was not aminoacylated in the presence of aminoacylo-tRNA synthetases.

Electrophoresis, Polyacrylamide Gel↗