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Endogenous protein substrates for prostatic acid phosphatase in human prostate
1Department of Diagnostic Immunology Research, Roswell Park Memorial Institute, New York State Department of Health, Buffalo 14263.
The Prostate
|January 1, 1991
Summary
Human prostatic acid phosphatase (PAP) dephosphorylates a specific 83 kDa protein (pp83) in prostate tissues. PAP acts as a universal protein phosphatase, acting on serine, threonine, and tyrosine residues.
Area of Science:
- Biochemistry
- Molecular Biology
- Oncology
Background:
- Human prostatic acid phosphatase (PAP) is an enzyme found in the prostate.
- Identifying endogenous substrates is crucial for understanding PAP's function.
Purpose of the Study:
- To identify endogenous phosphoprotein substrates of PAP in prostate tissues.
- To characterize the phosphatase activity of PAP.
Main Methods:
- Phosphorylation of cellular proteins from various prostate tissues and cell lines.
- Dephosphorylation assays using purified PAP.
- Inhibition studies with L(+)-tartrate.
- Phosphoamino acid analysis.
Main Results:
- PAP preferentially dephosphorylated an 83 kDa cytosolic protein (pp83).
- Dephosphorylation of pp83 was observed in all prostate tissues and cell lines.
- L(+)-tartrate completely inhibited PAP's activity on pp83.
- pp83 is primarily dephosphorylated at serine/threonine residues.
- PAP demonstrated both phosphoserine/threonine and phosphotyrosine protein phosphatase activity.
Conclusions:
- pp83 is an endogenous substrate of PAP in the human prostate.
- PAP functions as a universal protein phosphatase, not specific to phosphotyrosine residues.