An acid phosphatase in the plasma membranes of human astrocytoma showing marked specificity toward phosphotyrosine protein

J. F. Leis, N. O. Kaplan

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115 Citations (Scopus)

Abstract

The plasma membrane from the human tumor astrocytoma contains an active acid phosphatase activity based on hydrolysis of p-nitrophenyl phosphate. Other acid phosphatase substrates - β-glycerophosphate, O-phosphorylcholine, and 5'-AMP - are not hydrolyzed significantly. The phosphatase activity is tartrate insensitive and is stimulated by Triton X-100 and EDTA. Of the three known phosphoamino acids, only free O-phosphotyrosine is hydrolyzed by the membrane phosphatase activity. Other acid phosphatases tested from potato, wheat germ, milk, and bovine prostate did not show this degree of specificity. The plasma membrane activity also dephosphorylated phosphotyrosine histone at a much greater rate than did the other acid phosphatases. pH profiles for free O-phosphotyrosine and phosphotyrosine histone showed a shift toward physiological pH, indicating possible physiological significance. Phosphotyrosine histone dephosphorylation activity was nearly 10 times greater than that seen for phosphoserine histone dephosphorylation, and K(m) values were much lower for phosphotyrosine histone dephosphorylation (0.5 μM vs. 10 μM). Fluoride and zinc significantly inhibited phosphoserine histone dephosphorylation. Vanadate, on the other hand, was a potent inhibitor of phosphotyrosine histone dephosphorylation (50% inhibiton at 0.5 μM) but not of phosphoserine histone. ATP stimulated phosphotyrosine histone dephosphorylation (160-250%) but inhibited phosphoserine histone dephosphorylation (95%). These results suggest the existence of a highly specific phosphotyrosine protein phosphatase activity associated with the plasma membrane of human astrocytoma.

Original languageEnglish (US)
Pages (from-to)6507-6511
Number of pages5
JournalProceedings of the National Academy of Sciences of the United States of America
Volume79
Issue number21 I
StatePublished - 1982
Externally publishedYes

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Phosphotyrosine
Astrocytoma
Acid Phosphatase
Histones
Cell Membrane
Phosphoserine
Proteins
Phosphoric Monoester Hydrolases
Phosphoamino Acids
Glycerophosphates
Protein Tyrosine Phosphatases
Vanadates
Phosphorylcholine
Phosphoprotein Phosphatases
Octoxynol
Adenosine Monophosphate
Solanum tuberosum
Edetic Acid
Triticum
Prostate

ASJC Scopus subject areas

  • General
  • Genetics

Cite this

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title = "An acid phosphatase in the plasma membranes of human astrocytoma showing marked specificity toward phosphotyrosine protein",
abstract = "The plasma membrane from the human tumor astrocytoma contains an active acid phosphatase activity based on hydrolysis of p-nitrophenyl phosphate. Other acid phosphatase substrates - β-glycerophosphate, O-phosphorylcholine, and 5'-AMP - are not hydrolyzed significantly. The phosphatase activity is tartrate insensitive and is stimulated by Triton X-100 and EDTA. Of the three known phosphoamino acids, only free O-phosphotyrosine is hydrolyzed by the membrane phosphatase activity. Other acid phosphatases tested from potato, wheat germ, milk, and bovine prostate did not show this degree of specificity. The plasma membrane activity also dephosphorylated phosphotyrosine histone at a much greater rate than did the other acid phosphatases. pH profiles for free O-phosphotyrosine and phosphotyrosine histone showed a shift toward physiological pH, indicating possible physiological significance. Phosphotyrosine histone dephosphorylation activity was nearly 10 times greater than that seen for phosphoserine histone dephosphorylation, and K(m) values were much lower for phosphotyrosine histone dephosphorylation (0.5 μM vs. 10 μM). Fluoride and zinc significantly inhibited phosphoserine histone dephosphorylation. Vanadate, on the other hand, was a potent inhibitor of phosphotyrosine histone dephosphorylation (50{\%} inhibiton at 0.5 μM) but not of phosphoserine histone. ATP stimulated phosphotyrosine histone dephosphorylation (160-250{\%}) but inhibited phosphoserine histone dephosphorylation (95{\%}). These results suggest the existence of a highly specific phosphotyrosine protein phosphatase activity associated with the plasma membrane of human astrocytoma.",
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T1 - An acid phosphatase in the plasma membranes of human astrocytoma showing marked specificity toward phosphotyrosine protein

AU - Leis, J. F.

AU - Kaplan, N. O.

PY - 1982

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N2 - The plasma membrane from the human tumor astrocytoma contains an active acid phosphatase activity based on hydrolysis of p-nitrophenyl phosphate. Other acid phosphatase substrates - β-glycerophosphate, O-phosphorylcholine, and 5'-AMP - are not hydrolyzed significantly. The phosphatase activity is tartrate insensitive and is stimulated by Triton X-100 and EDTA. Of the three known phosphoamino acids, only free O-phosphotyrosine is hydrolyzed by the membrane phosphatase activity. Other acid phosphatases tested from potato, wheat germ, milk, and bovine prostate did not show this degree of specificity. The plasma membrane activity also dephosphorylated phosphotyrosine histone at a much greater rate than did the other acid phosphatases. pH profiles for free O-phosphotyrosine and phosphotyrosine histone showed a shift toward physiological pH, indicating possible physiological significance. Phosphotyrosine histone dephosphorylation activity was nearly 10 times greater than that seen for phosphoserine histone dephosphorylation, and K(m) values were much lower for phosphotyrosine histone dephosphorylation (0.5 μM vs. 10 μM). Fluoride and zinc significantly inhibited phosphoserine histone dephosphorylation. Vanadate, on the other hand, was a potent inhibitor of phosphotyrosine histone dephosphorylation (50% inhibiton at 0.5 μM) but not of phosphoserine histone. ATP stimulated phosphotyrosine histone dephosphorylation (160-250%) but inhibited phosphoserine histone dephosphorylation (95%). These results suggest the existence of a highly specific phosphotyrosine protein phosphatase activity associated with the plasma membrane of human astrocytoma.

AB - The plasma membrane from the human tumor astrocytoma contains an active acid phosphatase activity based on hydrolysis of p-nitrophenyl phosphate. Other acid phosphatase substrates - β-glycerophosphate, O-phosphorylcholine, and 5'-AMP - are not hydrolyzed significantly. The phosphatase activity is tartrate insensitive and is stimulated by Triton X-100 and EDTA. Of the three known phosphoamino acids, only free O-phosphotyrosine is hydrolyzed by the membrane phosphatase activity. Other acid phosphatases tested from potato, wheat germ, milk, and bovine prostate did not show this degree of specificity. The plasma membrane activity also dephosphorylated phosphotyrosine histone at a much greater rate than did the other acid phosphatases. pH profiles for free O-phosphotyrosine and phosphotyrosine histone showed a shift toward physiological pH, indicating possible physiological significance. Phosphotyrosine histone dephosphorylation activity was nearly 10 times greater than that seen for phosphoserine histone dephosphorylation, and K(m) values were much lower for phosphotyrosine histone dephosphorylation (0.5 μM vs. 10 μM). Fluoride and zinc significantly inhibited phosphoserine histone dephosphorylation. Vanadate, on the other hand, was a potent inhibitor of phosphotyrosine histone dephosphorylation (50% inhibiton at 0.5 μM) but not of phosphoserine histone. ATP stimulated phosphotyrosine histone dephosphorylation (160-250%) but inhibited phosphoserine histone dephosphorylation (95%). These results suggest the existence of a highly specific phosphotyrosine protein phosphatase activity associated with the plasma membrane of human astrocytoma.

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