Fig. 1. Comparison of SNARE expression in RPE-J cells and rat kidney or brain by western blot analysis. Equal protein amounts of total homogenates of differentiated RPE-J cells, rat kidney or rat brain (1/10 of the protein) were separated by SDS-PAGE and analyzed by western blot with specific antibodies as indicated. Note that syntaxin 3 is virtually undetectable in RPE-J cells. By contrast, the expression levels of syntaxins 2 and 4 are roughly comparable between RPE-J and rat kidney. SNAP-23, cellubrevin and endobrevin are expressed in both kidney and RPE-J. RPE-J cells also express the `neuron-specific' t-SNAREs syntaxin 1A and 1B but there is no detectable SNAP-25.