Fig. 2. NPP3 and NPP1 differ with respect to their solubility in cold non-ionic detergents. (A,B) Scanning confocal micrographs of MDCK cells stably transfected with NPP3 (A), or NPP1 (B) cDNAs. NPP3 and NPP1 were labeled with specific monoclonal antibodies followed by secondary FITC-conjugated antibodies. Projections (xy and xz views) are shown. Bars, 10 µm. (C,D) DRM association of NPP3 and NPP1. MDCK-NPP3 and MDCK-NPP1 cell homogenates were extracted with 0.5% Triton X-100, or 0.5% Lubrol WX, or 0.5% Brij 58 at 4°C, and separated on sucrose gradients. The distribution of NPP3 (C) and NPP1 (D) was analyzed by immunoblotting after immunoprecipitation from each fraction. Typical immunoblots are shown. Bar charts show quantification of the DRM-associated protein (fractions 3-6) (DRM) and soluble protein (fractions 7-12) (Sol) from the blots. Results are means ± s.d. of at least three independent experiments.