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. 2019 Aug 7;7:146. doi: 10.3389/fcell.2019.00146

Figure 3.

Figure 3

Scheme of ER-to-Golgi transport according to the VM and CMPM. Upper section: (A) Formation of COPII-coated bud. (B) Formation of a COPII-dependent protrusion, which might be partially coated with COPII, for a megacargo inside this protrusion. A COPI vesicle recycles the resident ER proteins. Middle section: (A) Movement of COPII-dependent vesicles one after another toward the Golgi complex. (B) Formation of a vesicle aggregate that moves toward the Golgi complex. Fusion of a COPI vesicle with the formation of a ER-to-Golgi carrier. (D) Delivery and fusion of the COPII vesicle to the intermediate compartment. (E) Movement of the ER protrusion. (F) Fusion of the ER protrusion, with the formation of common carrier. (G) Fusion of the protrusion-dependent ER-to-Golgi carrier with the intermediate ERGIC compartment. Lower section: Different possibilities for the final delivery of ER-to-Golgi carriers to the Golgi complex. Left: According to the pure VM: (A) The additional round of COPII-dependent vesicle formation from the ER-to-Golgi carrier from the intermediate compartment. (B) Delivery of a new vesicle to the Golgi complex. (C) According to the CMPM: COPII vesicles or ER protrusions form the new cis-Golgi cisterna. (D) According to the bolus-like mechanism within the framework of the KARM: Movement of the carrier along the ER-Golgi tubule.