Reactivation on membrane activity from germinated and ungerminated radish seeds

Reactivation by polar lipidis of membrane ATPase activity from germinated and ungerminated radish seeds. M. COCUCCI. Centro di Studio del C.N.R. per la Biologia Cellulare e Molecolare delle Pi ante Istituto di Scienze Botaniche Universita di Milano. The early phases of germination of radish (Raphanus saf;vus L.) seed are cha racterized by the activation of plasmamembrane functions such as K + uptake. acid secretion, transitory increase of negati ve transmembrane potential. T here is evidence suggesting that these functions may depend, in this and in other materials, on the acti vity of a Mg++ , K+ activa ted, dicycJohexylcarbodiimide-sensitive plasmamembrane ATPase. This ATPa ~e activity increases in the membrane fraction in the fi rst 23h of germination (+ 300%). The removal of polar lipids from membrane preparations by cholate treatment almost completely suppreses the ATPase activity. The subsequent addition of polar Lip ids from radish seeds reconstitutes the ATPase activity. Polar lipids from germinated seeds are more active than that from ungerminated seeds. This data suggest that variation of polar lipids composition of the membrane, during early phases of germination. may be an important factor in determining the rise in ATPase activity duri ng early phases of germination.