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. Author manuscript; available in PMC: 2015 May 14.
Published in final edited form as: Front Biosci (Landmark Ed). 2011 Jun 1;16:2598–2621. doi: 10.2741/3875

Figure 8.

Figure 8

PHEX endoprotease activity and 60 kDa PHEX fragment content are higher in membranes from mineralized osteoblastic cultures versus un-mineralized controls. A, Crude membranes were isolated and assayed for PHEX endopeptidase activity with a specific fluorescent substrate assay as previously described (147). Cultures assayed were either mineralized by addition of BGP (● and *) or treated with AEBSF to block mineralization (■ and ◆) (188). Individual symbols on the graph represent duplicate analyses. Activity was normalized based on the protein content of membrane preparations. (Data obtained in collaboration with Drs. S. Liu and D. Quarles). B, Crude membranes from mineralizing cultures are enriched in the 60 kDa PHEX band. Comparing the data in Figures 8A and 8B leads to the conclusion that the 60 kDa PHEX band is catalytically active. KEY: +BGP, mineralized; +B + AEBSF, mineralization blocked with AEBSF; −BGP, unmineralized (without BGP); −BGP + AEBSF (without BGP but with AEBSF). (Data obtained in collaboration with Drs. S. Liu and D. Quarles.)