Figure 5.

Compensatory mutations to PSD-95 and stargazin reconstitute binding and clustering. (A) GST-fusion proteins show that stargazin with a point mutation in its PDZ-binding region (T321F) does not bind WT PSD-95, but does bind PSD-95 bearing a compensatory point mutation (H225V) in its second PDZ domain. (B) Confocal images of pyramidal cells expressing stargazin T321F GFP. Stargazin T321F GFP alone expressed diffusely (Top). Coexpression of untagged PSD-95 did not alter the diffuse localization of stargazin T321F (Middle). Cotransfection of an untagged compensatory PSD95 (PSD-95 H225V) caused robust synaptic localization of stargazin T321F GFP (Bottom). (Scale bar: 5 μm.)