Fig. 7.

FRIL image of simultaneous Cx35 presynaptic and Cx34.7 postsynaptic labeling in the same replica (R811). (A) Cx35 labeling (three 6-nm, arrowheads, two 18-nm, and two 20-nm gold) in a small gap junction hemiplaque viewed toward the CE on an RSN found ca. 450 μm form the M-cell. (B,C) Low and high magnification stereoscopic views of 11 M-cell gap junctions labeled for Cx34.7. A few 10-nm (rabbit) and 12-nm (chicken) gold beads label nine of the 11 gap junctions shown in B (from total of 81 gap junctions exposed in this LMCE/M-cell contact). (C) Higher magnification view of one large gap junction that is labeled by 10 10-nm and 12-nm gold beads, which are difficult to separately distinguish. Yellow overlays indicate glutamate receptor E-face particles in the RSN plasma membrane (A) and P-face pits representing where glutamate receptor proteins had been removed from the M-cell P-face (B,C). The 100% differential labeling in A vs. B and C (i.e., labeling for one connexin but no labeling for the other connexin) is consistent with heterotypic Cx35:Cx34.7 coupling. Note: Images A and C are at the same magnification, revealing that the gold beads for Cx35 vs. Cx34.7 are distinctly different in size. Calibration bars are 0.1 μm.