Showing papers by "Phillip A. Sharp published in 1978"
TL;DR: Correlation of the structure of two cytoplasmic spliced viral RNAs detected in CV-1 cells during the early phase of simian virus 40 (SV40) infection suggests that expression of the early SV40 genes is partially controlled at the level of splicing of RNAs.
Abstract: Biochemical methods are presented for determining the structure of spliced RNAs present in cells at low concentrations. Two cytoplasmic spliced viral RNAs were detected in CV-1 cells during the early phase of simian virus 40 (SV40) infection. One is 2200 nucleotides in length and is composed of two parts, 330 and 1900 nucleotides, mapping from ∼0.67 to ∼0.60 and from ∼0.54 to ∼0.14, respectively, on the standard viral map. The other is 2500 nucleotides long and also is composed of two parts, 630 and 1900 nucleotides mapping from ∼0.67 to ∼0.54 and from ∼0.54 to ∼0.14, respectively. Correlation of the structure of these mRNAs with the structure of the early SV40 proteins, small T antigen (17,000 daltons) and large T antigen (90,000 daltons), determined by others suggests that: (i) translation of the 2500-nucleotide mRNA yields small T antigen; (ii) translation of the 2200-nucleotide mRNA proceeds through the splice point in the RNA to produce large T antigen (and thus large T antigen is encoded in two separate regions of the viral genome); and (iii) the DNA sequences between ∼0.67 and ∼0.60 present in both mRNAs are translated in the same reading frame in both mRNAs to yield two separate gene products that have the same NH2-terminal sequence. Therefore, expression of the early SV40 genes is partially controlled at the level of splicing of RNAs.
625 citations
TL;DR: The structure of adenovirus 2 (Ad2) cytoplasmic RNAs produced during the early phase of infection is defined and it is suggested that, like the SV40 tumor antigens, the polypeptides encoded by these Ad2 mRNAs have an identical amino acid sequence at their N terminal ends, but have different C terminal sequences.
512 citations
TL;DR: A phage called lambdacol100 has been used to introduce the colicin E1 plasmid replicon into Escherichia coli previously treated with chloramphenicol to block protein synthesis as mentioned in this paper.
Abstract: A derivative of bacteriophage lambda containing a colicin E1 plasmid replicon was constructed by recombinant DNA techniques. This phage, lambdacol100, has two functional modes of DNA replication; it can replicate via either plasmid or phage replication systems. lambdacol100 has been used to introduce the colicin E1 plasmid replicon into Escherichia coli previously treated with chloramphenicol to block protein synthesis. Under these conditions, lambdacol100 DNA is replicated normally as a colicin E1 plasmid. This suggests that colicin E1 plasmid replication in vivo does not require any plasmid-encoded proteins.
62 citations
TL;DR: Using long reverse transcripts of Mo-MuLV, a region of nonhomology has been mapped by electron microscopic analysis of heteroduplexes formed with HIX 35S virion RNA by providing an internal visual marker for the 3' end of the genome.
46 citations
32 citations
TL;DR: A phage-plasmid hybrid was constructed for use as a recombinant DNA vector, allowing the propagation of cloned EcoRI restriction endonuclease fragments, and could be maintained at a copy number determined by the colicin E1 plasmid replicon and was also sensitive to amplification after chloramphenicol treatment.
Abstract: A phage-plasmid hybrid was constructed for use as a recombinant DNA vector, allowing the propagation of cloned EcoRI restriction endonuclease fragments of about 2 X 10(6) to 11 X 10(6) daltons The colicin E1 plasmid replicon was fused to the left arm of a lambdagt generalized transducing phage with a thermolabile repressor, yielding a genome which could be replicated either by phage lambda functions or via the colicin E1 plasmid replicon At the nonpermissive temperature, phage functions were derepressed and phage growth occurred lytically Alternatively, at the permissive temperature, lambda functions were repressed and the vector replicated as a covalently closed circular plasmid The phage-plasmid hybrid vector could be maintained at a copy number determined by the colicin E1 plasmid replicon and was also sensitive to amplification after chloramphenicol treatment An EcoRI fragment of Escherichia coli DNA encoding genes of the arabinose operon also was inserted into the central portion of the vector
5 citations