Bisphosphate nucleosides contain phosphate or pyrophosphate at both the 3' and 5' positions. In bacteria, phosphorylation at the 3' position occurs during periods of stress, such as starvation, and nucleoside bisphosphates bind to RNA polymerase to decrease the synthesis of translational machinery and increase the transcription of biosynthetic genes until amino acid and fatty acid levels within the cell return to normal levels. Eukaryotic cells also produce pGp upon their transition from G1 to S-Phase, which allows for building blocks to re-accumulate and new protein synthesis to occur.