Iodide (I-) Enters and Exits (IMAGE) Institute for Basic Science Caption Cells are treated with iodide-sensitive yellow fluorescent proteins (YFP-HEK-293T cells) which are fluorescent only in the absence of I- (A). IBS scientists observed that the addition of PB-1A channels did not interfere with the fluorescence (B), but one hour later, when they added I- (as Sodium iodide, NaI), the fluorescence was quenched (C). The NaI solution was then removed, and the fluorescence reappeared after 30 minutes, indicating that I- diffused out of the cell through the PB-1A channels (D). Credit IBS Usage Restrictions None License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.