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Full-Text Articles in Life Sciences
An Enzymatic Activity In Uninfected Cells That Cleaves The Linkage Between Poliovirion Rna And The 5' Terminal Protein, Victor Ambros, Ralf Pettersson, David Baltimore
An Enzymatic Activity In Uninfected Cells That Cleaves The Linkage Between Poliovirion Rna And The 5' Terminal Protein, Victor Ambros, Ralf Pettersson, David Baltimore
Victor R. Ambros
The 5' terminal protein (VPg) on poliovirion RNA can be removed by cell-free extracts from a variety of uninfected cells. This soluble enzymatic activity is found in both nuclear and cytoplasmic extracts of heLa cells and is activated by Mg++. The enzyme activity cleaves the tyrosine-phosphate bond that links the protein to the RNA. In a partially purified form it has insufficient nonspecific protease or nuclease activity to account for its action. The existence of this enzyme implies that poliovirus RNA is translated in cell-free extracts in a form that lacks the 5' terminal protein. The role of this enzyme …
Protein Is Linked To The 5' End Of Poliovirus Rna By A Phosphodiester Linkage To Tyrosine, Victor Ambros, David Baltimore
Protein Is Linked To The 5' End Of Poliovirus Rna By A Phosphodiester Linkage To Tyrosine, Victor Ambros, David Baltimore
Victor R. Ambros
Purification and partial characterization of the poliovirus RNA-linked protein (VPg) are described. VPg has been freed from the RNA by ribonuclease digestion and phenol extraction. Gel filtration chromatography of VPg-pUp (labeled with 32P) in 0.5% sodium dodecyl sulfate or 6 M guanidine HCl indicates that it has a molecular weight of about 12,000. VPg is bound to the 5' end of poliovirion RNA by a phosphodiester bond between a tyrosine residue in the VPg molecule and the 5'-terminal uridine. After acid hydrolysis of [3H]tyrosine-labeled VPg-pU, free tyrosine can be released by venom phosphodiesterase. Acid hydrolysis of VPg-p labeled with either …
Identification Of A Protein Linked To Nascent Poliovirus Rna And To The Polyuridylic Acid Of Negative-Strand Rna, Ralf F. Pettersson, Victor R. Ambros, David Baltimore
Identification Of A Protein Linked To Nascent Poliovirus Rna And To The Polyuridylic Acid Of Negative-Strand Rna, Ralf F. Pettersson, Victor R. Ambros, David Baltimore
Victor R. Ambros
A protein similar to that previously demonstrated on poliovirus RNA and replicative intermediate RNA (VPg) was found on all sizes of nascent viral RNA molecules and on the polyuridylic acid isolated from negative-strand RNA. 32P-labeled nascent chains were released from their template RNA and fractionated by exclusion chromatography on agarose. Fingerprint analysis using two-dimensional polyacrylamide gels of RNase T1 oligonucleotides derived from nascent chains of different lengths showed that a size fractionation of nascent chains was achieved. VPg was recovered from nascent chains varying in length from 7,500 nucleotides (full-sized RNA) to about 500 nucleotides. No other type of 5' …