(p)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 (tRNA) 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.
When the amino acid balance in the cell is restored, (p)ppGpp is hydrolysed by SpoT.