Proteolytic activation of the plant plasma membrane H(+)-ATPase by removal of a terminal segment.
Incubation of oat root plasma membrane vesicles in the presence of ATP with trypsin or chymotrypsin increased the rate of ATP hydrolysis and ATP-dependent proton pumping by the plasma membrane H(+)-ATPase. Proton pumping was stimulated more than 200%, whereas ATP hydrolytic activity was stimulated about 30%. The Km (ATP) for both proton pumping and ATP hydrolysis was lowered from about 0.3 mM to below 0.1 mM. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of trypsin-treated plasma membranes revealed a decrease in a 100-kDa band and the appearance of a 93-kDa band. Western blot analysis using antibodies against the H(+)-ATPase showed that both of these bands represented the H(+)-ATPase and suggested that a 7-kDa segment was released. Extensive treatment with carboxypeptidase A also activated the H(+)-ATPase indicating that the 7-kDa segment originated from the C terminus.
Palmgren
M G
MG
Department of Plant Biochemistry, University of Lund, Sweden.
Larsson
C
C
Sommarin
M
M
D000255:Adenosine Triphosphate / Q000378:metabolism; D002462:Cell Membrane / Q000201:enzymology; D002918:Chymotrypsin / Q000378:metabolism*; D002523:Edible Grain / Q000201:enzymology; D004789:Enzyme Activation; D007700:Kinetics; D010944:Plants / Q000201:enzymology*; D011499:Protein Processing, Post-Translational; D006180:Proton-Translocating ATPases / Q000235:genetics* / Q000378:metabolism; D012265:Ribonucleotides / Q000494:pharmacology; D014357:Trypsin / Q000378:metabolism*
D012265:Ribonucleotides; D000255:Adenosine Triphosphate; D002918:Chymotrypsin; D014357:Trypsin; D006180:Proton-Translocating ATPases