File Name : figure s1.pdf Caption : figure s1: representative images from a frap experiment with atto-488 labelled cpk. frap experiments were performed by taking videos of planar lipid membranes with inserted atto-488 labelled cpk using a tirf microscope. (left) the labelled membrane pre-bleaching. (centre) the labelled membrane post-bleaching. (right) the membrane after maximum recovery has taken place. frap experiments showed a mean recovery of 51% ± 3% (n=6). File Name : figure s2.pdf Caption : figure s2: complete histogram of the fusion time of individual particles. the histograms were fitted with a bi-exponential decay function. the bi-exponential decay function is fit with 4 variables: with a and b being the amplitudes and k1 and k2 being the decay constants, with the range indicating the standard error. r2 shows the coefficient of determination of the fit.