Pyridoxal phosphate-binding protein (PLPBP)

Pyridoxal phosphate-binding protein (PLPBP) is an evolutionarily conserved, single-domain regulatory protein with a fold type III structure (TIM-barrel) and no known enzymatic activity[1]. It binds the active form of vitamin B6 (pyridoxal 5'-phosphate, PLP), keeping PLP solvent-exposed for possible shuttling to PLP-dependent enzymes. PLPBP is critical in maintaining cellular PLP levels, thus ensuring activity of the many PLP-dependent enzymes that support amino acid and other core metabolic processes[1][5]. Disruption of PLPBP affects vitamin B6 homeostasis and can lead to accumulation of toxic vitamin B6 intermediates, especially pyridoxine 5'-phosphate, resulting in pleiotropic phenotypes, notably vitamin B6-dependent epilepsy in humans[3][4][5]. The protein may also play roles in cell division and cytoskeleton integrity, although these are less well characterized. PLPBP is not an enzyme or receptor and is not directly targeted by therapeutic drugs, but its function is essential in cellular vitamin B6 handling and metabolic regulation[1][5]. Deficiency or mutation may be addressed by vitamin B6 supplementation to supply the necessary cofactor for downstream enzymes[3][4].

Other names

Pyridoxal phosphate homeostasis proteinProline synthase co-transcribed bacterial homolog proteinPROSCYggS (bacterial homolog)PipY (cyanobacterial homolog)