Abstract
P36 is a major substrate of the tyrosine protein kinases. P36 isolated from bovine intestine was used in phosphorylation reactions with pp60src. Phosphorylation was stimulated 3-5-fold by Ca2+, however the Km was the same (2.5 microM) at high or low Ca2+. Although the level of free Ca2+ needed for this enhanced phosphorylation was 10(-4)-10(-3) M, phosphatidylserine shifted the Ca2+ sensitivity to the 10(-6)-10(-5) M range. Independent evidence suggested that p36 interacts directly with liposomes containing phosphatidylserine. This raises the possibility that p36, like c-kinase, is a Ca2+-activated, phospholipid-dependent protein.
Publication types
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Research Support, U.S. Gov't, P.H.S.
MeSH terms
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Animals
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Annexins
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Calcium / pharmacology*
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Cattle
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Intestines / analysis
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Kinetics
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Membrane Proteins / metabolism*
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Oncogene Protein pp60(v-src)
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Phosphatidylinositols / pharmacology
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Phosphatidylserines / pharmacology
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Phospholipids / pharmacology*
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Phosphorylation
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Phosphotyrosine
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Protein-Tyrosine Kinases / metabolism
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Retroviridae Proteins / metabolism*
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Tyrosine / analogs & derivatives
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Tyrosine / metabolism
Substances
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Annexins
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Membrane Proteins
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Phosphatidylinositols
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Phosphatidylserines
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Phospholipids
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Retroviridae Proteins
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Phosphotyrosine
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Tyrosine
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Protein-Tyrosine Kinases
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Oncogene Protein pp60(v-src)
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Calcium