The H+-ATPase purified from maize root plasma membranes retains fusicoccin in vivo activation.
The activity of 'P-type' ATPases is modulated through the C-terminal autoinhibitory domain. The molecular bases of the regulation are unknown. Their understanding demands functional and structural studies on the activated purified enzyme. In this paper the plasma membrane H+-ATPase from maize roots activated in vivo by fusicoccin was solubilised and fractionated by anion-exchange HPLC. Results showed that the H+-ATPase separated from fusicoccin receptors retained fusicoccin activation and that it was more evident after enzyme insertion into liposomes. These data suggest that fusicoccin stimulation does not depend on a direct action of the fusicoccin receptor on the H+-ATPase, but rather, fusicoccin brings about a permanent modification of the H+-ATPase which very likely represents a general regulatory mechanism for 'P-type' ATPases.
Marra
M
M
Dipartimento di Biologia, Università di Roma 'Tor Vergata', Roma, Italy.
Fogliano
V
V
Zambardi
A
A
Fullone
M R
MR
Nasta
D
D
Aducci
P
P
D002462:Cell Membrane / Q000201:enzymology*; D004789:Enzyme Activation; D006027:Glycosides / Q000494:pharmacology*; D006863:Hydrogen-Ion Concentration; D008081:Liposomes; D018517:Plant Roots / Q000201:enzymology; D017494:Proton Pumps / Q000378:metabolism; D006180:Proton-Translocating ATPases / Q000302:isolation & purification / Q000378:metabolism*; D011956:Receptors, Cell Surface; D003313:Zea mays / Q000201:enzymology*
D006027:Glycosides; D008081:Liposomes; D017494:Proton Pumps; D011956:Receptors, Cell Surface; C007808:fusicoccin; D006180:Proton-Translocating ATPases