FIGURE 4:

A DxY motif contributes to Mep3 trafficking. (A) Full-length Mep3 sequence was analyzed using the SPOCTOPUS membrane protein topology prediction algorithm. The DxY motif (aa 431–433) is indicated (Inside, cytoplasmic; Outside, extracellular; TM-Helix, transmembrane). (B) Localization of Mep3-GFP in WT or syp1Δ cells transformed with empty high-copy vector, high-copy SYP1, or high-copy SYP1 lacking the μHD was examined by live-cell fluorescence microscopy. Scale bar, 2 μm. (C) Fluorescence intensity from cells expressing Mep3-pHluorin was quantified for each condition; intensity values were corrected for cell size and expressed in arbitrary units (a.u.). Error bars indicate mean ± SEM; *p < 0.05, ****p < 0.0001 compared with WT. (D) Cells expressing full-length Mep3-GFP, Mep3^Δ430-GFP, or Mep3^Δ433-GFP in WT and syp1Δ backgrounds were grown on minimal medium and imaged via live-cell fluorescence microscopy. Scale bar, 2 μm. (E) Intensity of Mep3-pHluorin for each condition was quantified; intensity values were corrected for cell size and expressed in arbitrary units (a.u.). Error bars indicate mean ± SEM; *p < 0.05, ****p < 0.0001 compared with WT.