Recombinant Human FGF23

FGF-23 is a protein of ∼30 kDa that is proteolytically processed to generate smaller N-terminal (18 kDa) and C-terminal (12 kDa) fragments. The N-terminal fragment of FGF-23 contains the FGF receptor (FGFR)-binding domain. In vivo studies using synthetic peptides have indicated that neither of the processed N-terminal or C-terminal fragments of FGF-23 can influence serum phosphate levels. FGF-23 can decrease the activity of NaPi-2a and NaPi-2c cotransporters to reduce renal phosphate reabsorption and thereby can increase urinary phosphate excretion. Similarly, FGF-23 can suppress the expression of 1-alpha-hydroxylase to reduce the production of the active vitamin D metabolite 1,25(OH)2D. Moreover, FGF-23 can also induce 24- hydroxylase, which degrades 1,25(OH)2D