Fig. 6.

Snapin enhances AQP2 transport activity via syntaxin-3. A: tracer urea uptake was measured into oocytes injected with the indicated cRNAs. Values are means ± SD obtained from 10 individual oocytes; the results were all the same in 3 different experimental series. There was no stimulating effect of syntaxin-4 (with or without snapin present) on AQP2 activity. However, in the absence of snapin, syntaxin-3 enhanced AQP2 activity by ∼50%, and in combination, syntaxin-3 and snapin enhanced AQP2 activity 4-fold. Also, no stimulation was observed in the presence of SNAP23/syntaxin alone or snapin alone (data not shown). B: confirmation of expressed proteins by Western blotting.