In order to vary the degree of membrane curvature, we pull membrane tubes (tethers) from lipid model membranes (giant vesicles) via a combination of micropipette aspiration and a membrane-attached bead. Tether radii were measured using a stepwise pulling and releasing method. Fluorescence intensities of tether were measured by confocal fluorescence imaging in a plane orthogonal to the membrane tether. By correlating tether radii with tether intensities, we found no curvature sorting for double leaflets or outer leaflet labeled DiI derivatives down to the radii about 10nm, Cholera Toxin subunit B (CTB) prefers binding to low curvature membrane. We furthermore examined the diffusion of DiO and CTB in membrane tubes by Fluorescence Recovery after Photobleaching.