title: Kinetically distinct sorting pathways through the Golgi exhibit different requirements for Arf1.
abstract: To investigate the role of cytoplasmic sequences in directing transmembrane protein trafficking through the Golgi, we analyzed the sorting of VSV tsO45 G fusions with either the native G cytoplasmic domain (G) or an alternative cytoplasmic tail derived from the chicken AE1-4 anion exchanger (G(AE) ). At restrictive temperature G(AE) and G accumulated in the ER, and upon shifting the cells to permissive temperature both proteins folded and underwent transport through the Golgi. However, G(AE) and G did not form hetero-oligomers upon the shift to permissive temperature and they progressed through the Golgi with distinct kinetics. In addition, the transport of G through the proximal Golgi was Arf1 and COPI-dependent, while G(AE) progression through the proximal Golgi was Arf1 and COPI-independent. Although Arf1 did not regulate the sorting of G(AE) in the cis-Golgi, Arf1 did regulate the exit of G(AE) from the TGN. The trafficking of G(AE) through the Golgi was similar to that of the native AE1-4 anion exchanger, in that the progression of both proteins through the proximal Golgi was Arf1-independent, while both required Arf1 to exit the TGN. We propose that the differential recognition of cytosolic signals in membrane-spanning proteins by the Arf1-dependent sorting machinery may influence the rate at which cargo progresses through the Golgi.
authors.affiliation: Department of Microbiology, Immunology, and Biochemistry, University of Tennessee Health Science Center, Memphis, TN, 38163, USA.
authors.forename: Michael A
authors.initials: MA
authors.lastname: Whitt
authors.forename: Michelle E
authors.initials: ME
authors.lastname: Cox
authors.forename: Rita
authors.initials: R
authors.lastname: Kansal
authors.forename: John V
authors.initials: JV
authors.lastname: Cox
mesh_terms: D020823:ADP-Ribosylation Factor 1 / Q000378:metabolism*; D000818:Animals; D001457:Anion Exchange Protein 1, Erythrocyte / Q000378:metabolism; D019556:COS Cells; D002460:Cell Line; D002645:Chickens; D002522:Chlorocebus aethiops; D020755:Coat Protein Complex I / Q000378:metabolism; D003593:Cytoplasm / Q000378:metabolism; D003600:Cytosol / Q000378:metabolism; D004285:Dogs; D004721:Endoplasmic Reticulum / Q000378:metabolism; D006056:Golgi Apparatus / Q000378:metabolism*; D007700:Kinetics; D061985:Madin Darby Canine Kidney Cells; D008565:Membrane Proteins / Q000378:metabolism; D017434:Protein Structure, Tertiary / Q000502:physiology; D021381:Protein Transport / Q000502:physiology*; D015398:Signal Transduction / Q000502:physiology*
chemical_list: D001457:Anion Exchange Protein 1, Erythrocyte; D020755:Coat Protein Complex I; D008565:Membrane Proteins; D020823:ADP-Ribosylation Factor 1
keywords: Arf1; COPI; Golgi; VSV G; anion exchanger; sorting signals