PubMed · 13434377
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K I MARKOV, G K SAEV. 1957. [Penicillin, a specific growth factor for staphylococci].. https://pubmed.ncbi.nlm.nih.gov/13434377/
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Vaccinia virus growth factor (VGF) is encoded by an early gene located near the border between the terminal inverted repeats and the internal unique region of the viral genome. It has been suggested that secreted VGF may serve to stimulate the metabolism of neighboring uninfected cells, thereby increasing the capacity of these cells to support viral replication. In this study, we cloned and sequenced the VGF gene of vaccinia virus strain Tian Tap. The analytical results indicated that VGF of strain Tian Tan possessed the core sequences of Epidermal growth factor superfamily, and more closely related to that of strain WR than to those of other orthopoxvirus strains. Overall deduced amino acid divergence of 4.3% was observed between Tian Tan and WR VGF protein, while divergences ranged from 10% to 20% compared to other orthopoxviruses strains. Most of the amino acid substitutions were found within signal peptide and transmembrane regions, but were not present in secreted ligand domain. It was striking that the amino acid sequence deduced from the ORF TB22L which located within the right terminal region of genome was identical to VGF protein amino acids 67-140, suggesting that ORF TB22L may be derived from the seconed copy of VGF gene of strain Tian Tan.
Saccharomyces cerevisiae was examined for tyrosine kinase activity in vitro because this organism offers molecular and genetic approaches for analyzing the role of tyrosine phosphorylation in cellular growth control that are unavailable in higher eukaryotes. Yeast extracts phosphorylated a random copolymer (glutamic acid:tyrosine, 80:20) at tyrosine in a reaction that was linear with respect to time and protein concentration. In the absence of added copolymer, phosphotyrosine was 0.1 percent of the total phosphoamino acids labeled with [gamma-32P]adenosine triphosphate in endogenous yeast proteins. However, specific activities of these reactions were low (approximately 1 percent of those in extracts of chick embryo fibroblasts). Lack of significant incorporation of label from [alpha-32P]adenosine triphosphate into the copolymer or endogenous yeast proteins demonstrated that nucleotide interconversion, adenylylation, and subsequent hydrolysis could not account for the generation of phosphotyrosine observed.
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