Erythrose-4-phosphate (E4P) is
an intermediate of the pentose phosphate pathway. It also is an
intermediate in the Calvin cycle (photosynthesis). Erythrose-4-phosphate
is produced by action of the enzyme transaldolase
in the reaction below:
Sedoheptulose-7-Phosphate + Glyceraldehyde-3-Phosphate <=> E4P + Fructose-6-Phosphate
In addition, erythrose-4-phosphate is involved in the biosynthesis of aromatic amino acids. All of the carbons in phenylalanine and tyrosine are derived from erythrose-4-phosphate and phosphoenolpyruvate.
2. CO2 Fixation