PHEX (PEX, Phosphate-regulating Gene with Homologies to Endopeptidases on the X Chromosome)

The amyloid beta-peptide (Ab) of 39-43aa (Ab40, Ab42, Ab43) is constitutively produced in brain upon proteolysis of the b-amyloid precursor protein (APP). In the young and healthy humans, Ab is rapidly catabolized before it can be deposited in the brain. However, upon aging or the onset of familial Alzheimer's Disease, alterations in either synthesis or degradation/clearance of Ab may contribute to amyloid depositions in the brain. Ab is susceptible to a number of in vivo and in vitro proteases like cathepsin-D and M-13 metalloproteases. The M-13 family includes several members of zinc-dependent proteases like damage-induced neuronal endopeptidase (DINE), product of phosphate regulating gene with homologies to endopeptidases on the X chromosome (PHEX), neutral endopeptidase 24.11 or neprilysin (NEP) and neprilysin-like proteases (NEPLs). NEPLs (alpha, beta, gamma) arise from the alternative splicing of a single NELPS gene and show ~54% sequence homology. M13 members are generally type II transmembrane proteins consisting of a single polypeptide chain with Zinc binding HEXXH motif, a short cytoplasmic tail, a transmembrane segment and an extra-cytoplasmic domain containing the enzyme active site. Phosphate regulating gene with homologies to endopeptidases on the X chromosome (PHEX) (formerly PEX) is a zinc-containing, type II integral membrane glycoprotein (~110kD; mouse/rat/human: 749aa; chromosome xp22.2-p22.1) with structural resemblance to M13 NEP proteases. In contrast to NEP, PHEX has very narrow substrate specificity and hydrolyzes parathroid hormone related peptide (PTHrP107-139). Compared to NEP, PHEX can proteolyze Ab40 (but not Ab42), at a very low rate and to a very poor extent and therefore is not a major in vivo peptidase for Ab. However, it might degrade Ab in Alzheimer patients where Ab is accumulated in excess and an Ab-degradative pathway, alternative to NEP, exists. PHEX is expressed lymphocytes and fetal brain but not in adult brain, placenta, skeletal muscle, pancreas, heart, liver and lung. Defects in PHEX are a cause of X-linked hypophosphatemic rickets (HYP). PHEX is implicated in bone and dentin mineralization and renal phosphate reabsorption.\n\nApplications: \nSuitable for use in ELISA and Western Blot. Other applications not tested.\n\nRecommended Dilution:\nWestern Blot: 1-10ug/ml using ECL. \nELISA: 1:10,000-1:100,000 using 50-100ng of control peptide/well.\nOptimal dilutions to be determined by the researcher.\n\nControl Peptide:\nP4070-68C: PHEX, Rat, Control Peptide (PEX, Phosphate-regulating Gene with Homologies to Endopeptidases on the X Chromosome)\n\nStorage and Stability:\nMay be stored at 4 degrees C for short-term only. For long-term storage, store at -20 degrees C. Aliquots are stable for at least 12 months at -20 degrees C. For maximum recovery of product, centrifuge the original vial after thawing and prior to removing the cap. Further dilutions can be made in assay buffer.

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SPECIFICATIONS

Catalog Number

P4070-68A

Size

50ug

Applications

ELISA, WB

Hosts

Rabbit

Reactivities

Rat

Form

Supplied as a liquid in PBS, 0.1% BSA, 40% glycerol.

P Type

Pab

Purity

Purified by immunoaffinity chromatography.

Isotype

IgG

References

1. Brandau, O., et al., Genome Res. 7: 573-585 (1997). 2. Du, L., et al., Genomics 36: 22-28 (1996). 3. Strom, T.M., et al., Hum. Mol. Genet. 6: 165-171 (1997). 4. Beck, L., et al., J. Clin. Invest. 99: 1200-1209 (1997). 5. Guo, R., et al., J. Bone mineral. Res. 12: 1009-1017 (1997). 6. Grieff, M., et al., BBRC 231: 635-639 (1997).

Additional Info

Recognizes PHEX. No significant sequence homology of PHEX11-P exists with NEP, NEPLs or other M13-family proteases. Species Sequence Homology: Mouse: 94%; human: 88%.