GAPDH is a 146 kDa tetramer metabolic enzyme within the glycolytic pathway that reversibly oxidatively phosphorylates glyceraldehyde 3-phosphate. It may have other additional functions in transcriptional activation. It is highly expressed due to its housekeeping functional role, and the prevalent expression of GAPDH has facilitated its use as an internal loading control – traditionally for mRNA expression comparisons – but also in protein studies.
