1. Differential Effects of G- and F-Actin on the Plasma Membrane Calcium Pump Activity.

VANAGAS L, DE LA FUENTE MC, DALGHI M, FERREIRA-GOMES M, ROSSI RC, STREHLER EE, MANGIALAVORI IC, ROSSI JP

CELL BIOCHEMISTRY AND BIOPHYSICS

HUMANA PRESS INC

Lugar: Oregon; Año: 2012 p. 1640 - 1649

1085-9195

Abstract We have previously shown that plasma membranecalcium ATPase (PMCA) pump activity is affectedby the membrane protein concentration (Vanagas et al.,Biochim Biophys Acta 1768:1641–1644, 2007). The resultsof this study provided evidence for the involvement of theactin cytoskeleton. In this study, we explored the relationshipbetween the polymerization state of actin and its effectson purified PMCA activity. Our results show that PMCAassociates with the actin cytoskeleton and this interactioncauses a modulation of the catalytic activity involving thephosphorylated intermediate of the pump. The state of actinpolymerization determines whether it acts as an activator oran inhibitor of the pump: G-actin and/or short oligomersactivate the pump, while F-actin inhibits it. The effects ofactin on PMCA are the consequence of direct interaction asdemonstrated by immunoblotting and cosedimentationexperiments. Taken together, these findings suggest thatinteractions with actin play a dynamic role in the regulationof PMCA-mediated Ca2? extrusion through the membrane.Our results provide further evidence of the activation–inhibition phenomenon as a property of many cytoskeleton-associated membrane proteins where the cytoskeletonis no longer restricted to a mechanical function but isdynamically involved in modulating the activity of integralproteins with which it interacts.