At P15, labelling for GIRK1 (Fig. 5C and H), GIRK2 (Fig. 5F and I) and GIRK3 (Fig. 6C, D and H) was found at both intracellular sites in dendritic shafts and spines (51, 49 and 62% of all particles examined for GIRK1, GIRK2 and GIRK3, respectively), and along the plasma membrane, where most (82% of GIRK1, 83% of GIRK2 and 57% of GIRK3) were found in postsynaptic compartments, and the rest (18% of GIRK1, 17% of GIRK2 and 43% of GIRK3) were found at presynaptic sites in axon terminals establishing asymmetrical synapses with dendritic spines (Figs 5H and I, and 6H). Finally, at P60, labelling for GIRK1 (Fig. 5D and H), GIRK2 (Fig. 5G and I) and GIRK3 (Fig. 6E-F and H) was found primarily along the plasma membrane, and less at intracellular sites (38, 35 and 46% of all particles examined for GIRK1, GIRK2 and GIRK3, respectively). Along the plasma membrane, most immunoparticles (84% of GIRK1, 86% of GIRK2 and 69% of GIRK3) were found in postsynaptic compartments, and the remainder (16% of GIRK1, 14% of GIRK2 and 31%
