Fig. 5. PSD-95/ion-channel clusters do not require PSD-95 multimerization but are reversibly dispersed by blocking palmitoylation of PSD-95. (A-D) PSD-95 clusters normally with a monomeric chimera containing the palmitoylated N-terminus of GAP-43 fused to PSD-95. (E,F) Incubating PSD-95/Kv1.4 co-transfected COS cells for 4 hours with 2-bromopalmitate disrupts PSD-95 ion channel clusters and causes both proteins to accumulate in perinuclear aggregates that resemble those formed (G,H) in cells co-transfected with Kv1.4 and the palmitoylation-deficient mutant of PSD-95 (C3,5S). (I,J) Treatment with palmitate as a control does not disrupt PSD-95/ion-channel clusters. (K,L) Somewhat smaller clusters are observed when Kv1.4 is co-transfected with a palmitoylation-deficient PSD-95 mutant that contains the paralemmin (PSD-95-prenyl) C-terminal consensus sequence for isoprenylation. (M,N) A 4-hour treatment with 20 µM 2-bromopalmitate does not disrupt ion channel clustering by PSD-95-prenyl. Bar, 10 µm.