Definitions for guanosine pentaphosphate
This page provides all possible meanings and translations of the word guanosine pentaphosphate
ppGpp, guanosine pentaphosphate or tetraphosphate is an alarmone which is involved in the stringent response in bacteria, causing the inhibition of RNA synthesis when there is a shortage of amino acids present. This causes translation to decrease and the amino acids present are therefore conserved. Furthermore, genes for amino acid uptake and biosynthesis are also upregulated. However, ppGpp influences the overall gene expression pattern in the cell so that many genes required for survival in stressful conditions are up-regulated. A complete absence of ppGpp generates its own unique phenotypic features in E. coli. These include multiple amino acid requirements, poor survival of aged cultures, aberrant cell division, morphology, and immotility, as well as being locked in a growth mode during entry into starvation. ppGpp is created via pppGpp synthase, also known as RelA, and is converted from pppGpp to ppGpp via pppGpp phosphohydrolase. RelA is associated with about every one in two hundred ribosomes and it becomes activated when an uncharged transfer RNA molecule enters the A site of the ribosome, due to the shortage of amino acid required by the tRNA. If a mutant bacterium is relA- it is said to be relaxed and no regulation of RNA production due to amino acid absence is seen.006
U.S. National Library of Medicine
Guanosine 5'-triphosphate 2'(3')-diphosphate. A guanine nucleotide containing five phosphate groups. Three phosphate groups are esterified to the sugar moiety in the 5' position and the other two in the 2' or 3' position. This nucleotide serves as a messenger to turn off the synthesis of ribosomal RNA when amino acids are not available for protein synthesis. Synonym: magic spot II.
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