Figure 7.

Anx4 binding to cytoplasmic lipid liposomes significantly reduces proton permeability. Proton permeability was measured by stopped-flow fluorometry under conditions in which liposomes were exposed to a pH gradient. pH-induced changes to fluorescence were monitored and proton permeability coefficients were calculated. Addition of 1 mM Ca²⁺ for 20 min had no effect on proton permeability at 25°C however addition of Ca²⁺ and annexin A4 together for 20 min significantly reduced proton permeability by 15%. At 37°C (right hand bars) proton permeability under control conditions was enhanced and the inhibitory effect of Anx4-binding resulted in a 20% inhibition (n = 3; mean ± SEM; P < 0.05).