This gene encodes a protein with a putative role in the localization of trans-Golgi network (TGN) membrane proteins. Mouse and rat homologs have been identified and studies of the homologous rat protein indicate a role in directing TGN localization of furin by binding to the protease's phosphorylated cytosolic domain. In addition, the human protein plays a role in HIV-1 Nef-mediated downregulation of cell surface MHC-I molecules to the TGN, thereby enabling HIV-1 to escape immune surveillance. [provided by RefSeq, Jul 2008].