Fig. 4.
PSD95β is not palmitoylated and fails to form plasma membrane clusters with Kv1.4. A, COS cells were transfected with constructs encoding PSD95α fused to GFP (PSD95α–GFP), PSD95β–GFP, or empty vector, and were metabolically labeled with [3H]palmitate. Cells were then lysed, proteins were separated by SDS-PAGE, and gels were analyzed by autoradiography (left panel) or Western blotting (right panel). Arrows indicate the predicted molecular weight for PSD95α–GFP and PSD95β–GFP.B, COS cells were transfected with Kv1.4 and PSD95β–GFP, SAP97–GFP, or PSD95α–GFP. Cells were fixed 48 hr after transfection and labeled with antibodies to Kv1.4. When coexpressed with PSD95β–GFP (a–c) or SAP97–GFP (d–f), Kv1.4 (red) accumulates on the nuclear membrane and on round perinuclear vesicles. In contrast, when transfected with PSD95α–GFP (g–i), Kv1.4 clusters in plasma membrane patches. Merged images are shown inpanels on right (c, f, i). Scale bar, 10 μm.