A plant protein kinase and plant microsomal H+ transport are stimulated by the ether phospholipid platelet-activating factor |
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Authors: | Georg Martiny-Baron Günther F E Scherer |
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Institution: | (1) Botanisches Institut der Universität Bonn, Venusbergweg 22, D-5300 Bonn 1, Germany |
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Abstract: | ATP-dependent H+ transport in microsomes from zucchini hypocotyls is stimulated by the ether lipid 1-0-alkyl-2-acetyl-sn-glycero-3-phosphocholine (platelet-activating factor = PAF) known as a hormone-like substance from mammals. The stimulation can only be observed when soluble cytosolic proteins are present. A soluble protein mediating the PAF-dependent H+ transport and a PAF-stimulated protein kinase are coeluted by DEAE-Sephacel chromatography. Stimulation of phosphorylation by PAF of a 55 kDa polypeptide without Ca2+ and, additionally, of a 35 kDa polypeptide in the presence of Ca2+ is observed in zucchini microsomal membranes. This is evidence for a novel phospholipid-stimulated protein kinase in plants. Phosphorylation of regulatory proteins may be involved in the stimulation of in vitro H+ transport by PAF.Abbreviations BTP
1,3-bis (tris(hydroxymethyl)-methylamino) propane
- DTT
dithiotreitol
- EGTA
ethylene glycol-bis (ß-aminoethyl ether)-N,N,N,N,-tetraacetic acid
- Mes
2-(N-morpholino) ethanesulfonic acid
- PAF
platelet-activating factor = 1-0-alkyl-2-acetyl-sn-glycero-3-phosphocholine
- SDS
sodium dodecylsulfate
- TCA
trichloroacetic acid |
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