Acetylation with succinimidyl acetate affects both the catalytic site and the regulation of the erythrocyte Ca2+ pump

CLAUDIA DONNET, ARIEL J. C ROSSI, JPFC ARIDE, HORACIO N. FERNANDEZ AND JUAN PABLO F. C. ROSSI*

BIOCHEMICAL JOURNAL

PORTLAND PRESS LTD

Lugar: Londres; Año: 1994 vol. 302 p. 133 - 140

0264-6021

Acetylation of lysine residues of the erythrocyte Ca2+ pump usingsuccinimidyl acetate (SA) led to its complete inactivation. In theabsence of any of the major activators of the pump (namelycalmodulin and acidic phospholipids), ATP fully protected thepump from inactivation by SA, with a KO5 of 13 ,uM. This valueis very close to the Km of the high-affinity site for ATP, thussuggesting that the residue(s) involved is(are) near or at thecatalytic site of the Ca2+-ATPase. Furthermore, the presence of500 ,uM ATP prevented the acetylation of about two residues permolecule of enzyme. Acetylation by SA also prevented theactivation of the Ca2+ pump by calmodulin, acidic phospholipids