title: Interaction between Sec7p and Pik1p: the first clue for the regulation of a coincidence detection signal.
abstract: Sec7p, a guanine nucleotide exchange factor, regulates the activation of small Arf GTPases, which function in the formation of distinct classes of transport carriers from the Golgi. The recruitment of a subset of Arf effectors depends on the cooperation between these GTPases and phosphatidylinositol 4-phosphate. Here, we show that the catalytic domain of Sec7p interacts with a conserved region of the Golgi phosphatidylinositol 4-kinase Pik1p. We found that Sec7p and Pik1p as well as its product, colocalize at the late Golgi. Gea1p/Gea2p, an alternative pair of Arf activators, do not bind to Pik1p and function on a different Golgi sub-compartment. Sec7p and Pik1p interact with each other and cooperate in the formation of clathrin-coated vesicles. This interaction reveals a distinct role for Sec7p among the Golgi Arf-GEFs and provides a working model for the coordinated generation of Arf-GTP and phosphatiylinositol 4-phosphate as dual signal for specific recruitment of clathrin coats to the late Golgi.
authors.affiliation: Max Planck Institute of Molecular Cell Biology and Genetics, Dresden D-01307, Germany.
authors.forename: Yvonne
authors.initials: Y
authors.lastname: Gloor
authors.forename: Mario
authors.initials: M
authors.lastname: Schöne
authors.forename: Bianca
authors.initials: B
authors.lastname: Habermann
authors.forename: Ebru
authors.initials: E
authors.lastname: Ercan
authors.forename: Mike
authors.initials: M
authors.lastname: Beck
authors.forename: Grit
authors.initials: G
authors.lastname: Weselek
authors.forename: Thomas
authors.initials: T
authors.lastname: Müller-Reichert
authors.forename: Christiane
authors.initials: C
authors.lastname: Walch-Solimena
mesh_terms: D019870:1-Phosphatidylinositol 4-Kinase / Q000378:metabolism*; D020727:ADP-Ribosylation Factors / Q000378:metabolism; D022163:Clathrin-Coated Vesicles / Q000378:metabolism; D005656:Fungal Proteins / Q000378:metabolism; D006056:Golgi Apparatus / Q000378:metabolism*; D020662:Guanine Nucleotide Exchange Factors / Q000378:metabolism*; D047468:Immunoprecipitation; D018129:Phosphatidylinositol Phosphates / Q000378:metabolism; D021381:Protein Transport / Q000502:physiology*; D029701:Saccharomyces cerevisiae Proteins / Q000378:metabolism*; D020798:Two-Hybrid System Techniques; D015003:Yeasts
chemical_list: D005656:Fungal Proteins; D020662:Guanine Nucleotide Exchange Factors; D018129:Phosphatidylinositol Phosphates; D029701:Saccharomyces cerevisiae Proteins; C066755:Sec7 guanine nucleotide exchange factors; C037178:phosphatidylinositol 4-phosphate; D019870:1-Phosphatidylinositol 4-Kinase; C441760:PIK1 protein, S cerevisiae; C116686:ARF2 protein, S cerevisiae; D020727:ADP-Ribosylation Factors