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. 2017 Aug 23;5:75. doi: 10.3389/fcell.2017.00075

Figure 2.

Figure 2

Model for ER exit site organization in different species. Arrows indicate Sar1 GTPase cycles. (A) A model for S. cerevisiae ER exit sites. Sec12 is dispersed throughout the ER. Sar1 accumulates at the rim of COPII-coated vesicles. (B) A model for P. pastoris ER exit sites. Sec16 is recruited to the ER exit site by interacting with COPII proteins. Sec12 is concentrated to the ER exit sites by interaction with Sec16. Sar1 accumulates at the ER exit sites. (C) A model for Homo sapiens ER exit sites. TANGO1 and Sec16 act as a scaffold to recruit COPII components and the membrane-spanning complex to the ER exit sites. Sar1 is efficiently activated by multiple Sec12 proteins within the cTAGE5/TANGO1/Sec12 complexes.