PACS-1a Background Information
Phosphofurin acidic cluster sorting protein-1 (PACS-1) is related to a family of cytosolic proteins, including HIV-1 Nef and ß-arrestin, that direct the internalization of cell surface receptors through the association with the clathrin/AP-2 sorting machinery (1,2). Similarily, PACS-1 participates in the localization of membrane proteins to the secretory pathway membrane compartments. Within the secretory pathway, the trans-Golgi network (TGN)/endosomal system is essential for sorting and distributing soluble and membrane associated proteins, and for producing lysosomes for exocytosis (3,4). PACS-1 is expressed from two distinct reading frames, which generate both a larger form, designated PACS-1a, and a smaller protein that is designated PACS-1b (1). PACS-1 proteins preferentially bind to the endoprotease, furin, as well as to the mannose 6-phosphate receptor, where they then facilitate the trafficking and localization of these proteins to the TGN, in a phosphorylation dependent manner (5,6).
