Figure 6. SH3GLB1 perfectly matches endocytic CHRN carriers and is capped by MAP1LC3A in an ATG7-dependent manner. Tibialis anterior muscles of WT (A–E and H–K) or atg7^−/− mice (F and G) were cotransfected with either SH3GLB1-mCherry and GFP-MAP1LC3A (A–G) or with SH3GLB1-mCherry and TRIM63-GFP (H–K). After 7 d, CHRNs were marked with BGT-AF647 and 24 h later, muscles were imaged using in vivo confocal microscopy. (A) Overview single optical slice showing the general codistribution of MAP1LC3A (green) and SH3GLB1 (red) in WT muscle. (B–E) Details from (A) showing exemplary colocalization patterns. While SH3GLB1 and CHRN colocalize perfectly and almost quantitatively, MAP1LC3A accompanies SH3GLB1- and CHRN-positive puncta either on 1 side (B), on 2 ends (C), or with more complex arrangements (D and E). (F and G) In atg7^−/− muscle MAP1LC3A is mostly distributed on sarcomeric striations and does not accompany SH3GLB1 and CHRN double-positive vesicles. (H–K) Maximum z-projection of a double-transfected fiber at the level of the NMJ. Fluorescence signals as indicated on top right angle of panels. In the overlay (I), TRIM63 signals are shown in green, SH3GLB1 in red, CHRN in blue. Triple-positive signals are indicated with red arrowheads.