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. Author manuscript; available in PMC: 2015 Jan 22.
Published in final edited form as: Biochem J. 2009 Jun 12;421(1):1–15. doi: 10.1042/BJ20081016

Figure 5. Working model of PACS-1/GGA3-regulated trafficking of CI-MPR.

Figure 5

GGA3 transports phosphorylated CI-MPR from the TGN to endosomes [180]. At the endosome, PACS-1 binds to the VHS domain of GGA3 through its FBR and recruits CK2 to phosphorylate Ser388 on GGA3 and phosphorylate Ser278 on PACS-1, thus releasing the autoregulatory domain and activating PACS-1 for cargo binding. CK2 may also phosphorylate additional sites on GGA3 [181] to promote release from endosomal membranes. Phosphorylated GGA3 dissociates, and activated PACS-1 binds to CI-MPR. Bound PACS-1 then recruits AP-1 to transport CI-MPR back to the TGN. It is not known whether CK2 bound to PACS-1 can phosphorylate the CI-MPR tail or other cargo molecules. An animated version of this Figure is available at http://www.BiochemJ.org/bj/421/0001/bj4210001add.htm.