Fig. 6
From: Steric exclusion and protein conformation determine the localization of plasma membrane transporters
Cartoon summarizing the main findings on diffusion and localization of plasma membrane proteins. a The plasma membrane (PM), cortical ER (cER) and two MCC/eisosomes (Sur7 in the membrane and Pil1 scaffold) are shown. The scaffolding of the MCCs is shown as blue half circle (Pil1); the blue small circles depict Sur7. DL, V i and V o refer to lateral diffusion and the rate of exo- and endocytosis, respectively. Left: in the absence of substrate (−KR): a fraction of Can1 (red) accumulates in (near) the MCC/eisosomes and has an apparent DL < 10−5 μm2/s, here indicated as “immobile”. The yellow cylinder depicts the fluorescent proteins fused to the transporters. The total concentration of Can1 is stable as delivery to (V i ) and removal from (V o ) the membrane are similar. Right: in the presence of substrate (+KR): Can1 takes a different conformation and dissociates from the MCC/eisosome and diffuses out. Next, Can1 is ubiquitinated and rapidly removed from the membrane (V o > V i ; indicated by thickness of arrow). b Large cytosolic domains exclude proteins from entering MCC/eisosomes, as shown for Pma1-YPet; c removal of the cytoplasmic domain enables (Pma1(∆392-679)-YPet) to enter the MCC/eisosome
