Calcified Tissue International

, Volume 57, Issue 5, pp 371–378 | Cite as

Phosphate regulates the stability of skeletal alkaline phosphatase activity in human osteosarcoma (SaOS-2) cells without equivalent effects on the level of skeletal alkaline phosphatase immunoreactive protein

  • J. R. Farley
Laboratory Investigations
Received:
Accepted:

Abstract

Inorganic phosphate (Pi) can regulate the level of skeletal alkaline phosphatase (ALP) activity in human osteoblast-like cells, but not by means of changes in transcription or release from the cell surface. The current studies were intended to determine whether (1) Pi affected the inactivation of ALP activity in human osteosarcoma (SaOS-2) cells; and (2) Pi-dependent changes in ALP-specific activity were associated with equal, concomitant changes in the level of ALP immunoreactive protein. The results of these studies revealed that Pi increased the stability of skeletal ALP activity without equivalent effects on the level of ALP immunoreactive protein. An increase in Pi (from 0 to 1.8 mmol/liter) caused a time-dependent increase in the amount of skeletal ALP activity in the SaOS-2 cells, without a parallel increase in the amount of skeletal ALP immunoreactive protein, and a decrease in Pi (from 1.8 to 0 mmol/liter) caused a time-dependent decrease in the amount of ALP activity, without a significant decrease in the total cellular content of ALP immunoreactive protein. Together, these observations suggest that Pi may alter the level of skeletal ALP activity in SaOS-2 cells by inhibiting a process of irreversible inactivation that does not effect equal, concomitant changes in the level of skeletal ALP immunoreactive protein.

Keywords

Osteosarcoma Phosphatase Activity Alkaline Phosphatase Activity Cellular Content Immunoreactive Protein 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.
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Copyright information

© Springer-Verlag New York Inc 1995

Authors and Affiliations

  • J. R. Farley
    • 1
  1. 1.Departments of Medicine and BiochemistryLoma Linda University, and the Jerry L. Pettis Memorial Veterans Medical CenterLoma LindaUSA

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