Identification of multiple cyclin subunits of human P-TEFb

Article Abstract:

A positive transcription elongation factor b (P-TEFb) may control transition from abortive to productive elongation through phosphorylation of the carboxy-terminal domain (CTD) of the largest subunit of RNA polymerase II. Drosophila P-TEFb has been shown to be a cyclin-dependent kinase (CDK9). Cloning of multiple cyclin subunits of human P-TEFb (T1 and T2) has been carried out. Cyclin T1 and T2 are expressed ubiquitously. Immunoprecipitation and immunodepletion experiments have indicated that cyclin T1 and T2 were associated in a mutually exclusive way with CDK9, almost all of which was associated with one or the other.

Protein kinases

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Conversion of the omega subunit of Escherichia coli RNA polymerase into a transcriptional activator or an activation target

Article Abstract:

In eukaryotes and in prokaryotes it appears that transcription can be activated by arbitrary contacts between DNA-bound proteins and components of transcriptional mechanisms. The Escherichia coli omega protein, which copurifies with RNA polymerase, can act as a transcriptional activator when covalent linkage to a DNA-binding protein occurs. It seems that the omega protein and RNA polymerase holoenzyme are associated in vivo. Evidence indicates that transcription can be activated by contact between a DNA-bound protein and any subunit of E. coli RNA polymerase.

Escherichia coli, DNA binding proteins

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Amino acid-amino acid contacts at the coopertivity interface of the bacteriophage lambda and P22 repressors

Article Abstract:

The bacteriophage lambda repressor and P22 repressors have been studied. Protein-protein interaction between DNA-bound dimers mediates cooperativity in which the repressors bind to adjacent and artificially separated operator sites. A genetic approach has been used to identify pairs of amino acids that interact at the dimer-dimer interface. Individual substitutions stop the interaction of the DNA-bound dimers, but changes in combination bring back interaction of lambda cI and P22c2 dimers.

Observations, Proteins, Amino acids, Amino acid structure-activity relationships, Bacteriophage lambda

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