Sodium-dependent phosphate transport protein 2A; Involved in actively transporting phosphate into cells via Na(+) cotransport in the renal brush border membrane. Probably mediates 70-80% of the apical influx; Belongs to the SLC34A transporter family.

Fibroblast growth factor 23 C-terminal peptide; Regulator of phosphate homeostasis. Inhibits renal tubular phosphate transport by reducing SLC34A1 levels. Upregulates EGR1 expression in the presence of KL (By similarity). Acts directly on the parathyroid to decrease PTH secretion (By similarity). Regulator of vitamin-D metabolism. Negatively regulates osteoblast differentiation and matrix mineralization.

Phosphate-regulating neutral endopeptidase PHEX; Peptidase that cleaves SIBLING (small integrin-binding ligand, N-linked glycoprotein)-derived ASARM peptides, thus regulating their biological activity. Cleaves ASARM peptides between Ser and Glu or Asp residues. Regulates osteogenic cell differentiation and bone mineralization through the cleavage of the MEPE-derived ASARM peptide. Promotes dentin mineralization and renal phosphate reabsorption by cleaving DMP1- and MEPE-derived ASARM peptides. Inhibits the cleavage of MEPE by CTSB/cathepsin B thus preventing MEPE degradation.

Sodium-dependent phosphate transport protein 2B; May be involved in actively transporting phosphate into cells via Na(+) cotransport. It may be the main phosphate transport protein in the intestinal brush border membrane. May have a role in the synthesis of surfactant in lungs' alveoli; Belongs to the SLC34A transporter family.

Klotho peptide; May have weak glycosidase activity towards glucuronylated steroids. However, it lacks essential active site Glu residues at positions 239 and 872, suggesting it may be inactive as a glycosidase in vivo. May be involved in the regulation of calcium and phosphorus homeostasis by inhibiting the synthesis of active vitamin D (By similarity). Essential factor for the specific interaction between FGF23 and FGFR1 (By similarity).

H(+)/Cl(-) exchange transporter 5; Proton-coupled chloride transporter. Functions as antiport system and exchanges chloride ions against protons. Important for normal acidification of the endosome lumen. May play an important role in renal tubular function; Belongs to the chloride channel (TC 2.A.49) family. ClC- 5/CLCN5 subfamily.

Ectonucleotide pyrophosphatase/phosphodiesterase family member 1, secreted form; Nucleotide pyrophosphatase that generates diphosphate (PPi) and functions in bone mineralization and soft tissue calcification by regulating pyrophosphate levels (By similarity). PPi inhibits bone mineralization and soft tissue calcification by binding to nascent hydroxyapatite crystals, thereby preventing further growth of these crystals. Preferentially hydrolyzes ATP, but can also hydrolyze other nucleoside 5' triphosphates such as GTP, CTP, TTP and UTP to their corresponding monophosphates with release [...]

Sodium-dependent phosphate transporter 2; Sodium-phosphate symporter which seems to play a fundamental housekeeping role in phosphate transport by absorbing phosphate from interstitial fluid for normal cellular functions such as cellular metabolism, signal transduction, and nucleic acid and lipid synthesis. In vitro, sodium-dependent phosphate uptake is not significantly affected by acidic and alkaline conditions, however sodium-independent phosphate uptake occurs at acidic conditions. May play a role in extracellular matrix, cartilage and vascular calcification. Functions as a retrovi [...]

1,25-dihydroxyvitamin D(3) 24-hydroxylase, mitochondrial; A cytochrome P450 monooxygenase with a key role in vitamin D catabolism and calcium homeostasis. Via C24- and C23-oxidation pathways, catalyzes the inactivation of both the vitamin D precursor calcidiol (25-hydroxyvitamin D(3)) and the active hormone calcitriol (1-alpha,25-dihydroxyvitamin D(3)). With initial hydroxylation at C-24 (via C24-oxidation pathway), performs a sequential 6-step oxidation of calcitriol leading to the formation of the biliary metabolite calcitroic acid. With initial hydroxylation at C-23 (via C23-oxidati [...]