PACS-1 binding to adaptors is required for acidic cluster motif-mediated protein traffic

Abstract

contributed equally to this work PACS-1 is a cytosolic protein involved in controlling the correct subcellular localization of integral membrane proteins that contain acidic cluster sorting motifs, such as furin and human immunode®ciency virus type 1 (HIV-1) Nef. We have now investigated the interaction of PACS-1 with heterotetrameric adaptor complexes. PACS-1 associates with both AP-1 and AP-3, but not AP-2, and forms a ternary complex between furin and AP-1. A short sequence within PACS-1 that is essential for binding to AP-1 has been identi®ed. Mutation of this motif yielded a dominantnegative PACS-1 molecule that can still bind to acidic cluster motifs on cargo proteins but not to adaptor complexes. Expression of dominant-negative PACS-1 causes a mislocalization of both furin and mannose 6-phosphate receptor from the trans-Golgi network, but has no effect on the localization of proteins that do not contain acidic cluster sorting motifs. Furthermore, expression of dominant-negative PACS-1 inhibits the ability of HIV-1 Nef to downregulate MHC-I. These studies demonstrate the requirement for PACS-1 interactions with adaptor proteins in multiple processes, including secretory granule biogenesis and HIV-1 pathogenesis.

In Vitro Formation of Recycling Vesicles from Endosomes Requires Adaptor Protein-1/Clathrin and Is Regulated by Rab4 and the Connector Rabaptin-5

“…In cells lacking the 1A subunit of AP-1, the mannose-6-phosphate receptor was found to accumulate in endosomes, rather than in the TGN, supporting an AP-1-dependent pathway from endosomes to the TGN (Meyer et al, 2000). Furthermore, retrograde transport of furin and other proteins containing acidic-cluster motifs from endosome-to-TGN is mediated by the protein PACS-1 and its interaction with AP-1 (Crump et al, 2001).…”

“…In cells lacking the 1A subunit of AP-1, the mannose-6-phosphate receptor was found to accumulate in endosomes, rather than in the TGN, supporting an AP-1-dependent pathway from endosomes to the TGN (Meyer et al, 2000). Furthermore, retrograde transport of furin and other proteins containing acidic-cluster motifs from endosome-to-TGN is mediated by the protein PACS-1 and its interaction with AP-1 (Crump et al, 2001).Some experiments directly argued against an involvement of clathrin-coated vesicles in receptor recycling. Perturbation of clathrin coat formation by regulated expression of a dominant-negative clathrin hub domain in HeLa cells reduced endocytosis by ϳ50% and caused perinuclear aggregation of early endosomes, but it reduced recycling by only ϳ20% (Bennett et al, 2001).…”

HIV-1 Nef Binds PACS-2 to Assemble a Multikinase Cascade That Triggers Major Histocompatibility Complex Class I (MHC-I) Down-regulation

“…The PACS proteins integrate secretory pathway traffic with endoplasmic reticulum (ER)-mitochondria communication and apoptotic pathways. They bind to acidic cluster motifs on client proteins to direct their localization to secretory and endosomal compartments or to mitochondria (22)(23)(24)(25)(26)(27)(28). The ability of the PACS proteins to mediate these manifold sorting steps is achieved by their interaction with COPI; with sorting adaptors, including AP-1, AP-3, and GGA3; or with regulatory proteins, including 14-3-3 proteins, protein kinase CK2, protein phosphatase 2A, and ubiquitin ligases (24, 26, 29 -32).…”

Effects of C-terminal deletions on cystic fibrosis transmembrane conductance regulator function in cystic fibrosis airway epithelia

“…Clusters of acidic residues have been observed in many proteins. In some cases they influence protein expression on the cell surface, an effect that can be mediated by binding to the cytosolic protein PACS-1 (40). Serines and threonines in acidic clusters are also targets for phosphorylation by casein kinase II.…”