title: The Arf family G protein Arl1 is required for secretory granule biogenesis in Drosophila.
abstract: The small G protein Arf like 1 (Arl1) is found at the Golgi complex, and its GTP-bound form recruits several effectors to the Golgi including GRIP-domain-containing coiled-coil proteins, and the Arf1 exchange factors Big1 and Big2. To investigate the role of Arl1, we have characterised a loss-of-function mutant of the Drosophila Arl1 orthologue. The gene is essential, and examination of clones of cells lacking Arl1 shows that it is required for recruitment of three of the four GRIP domain golgins to the Golgi, with Drosophila GCC185 being less dependent on Arl1. At a functional level, Arl1 is essential for formation of secretory granules in the larval salivary gland. When Arl1 is missing, Golgi are still present but there is a dispersal of adaptor protein 1 (AP-1), a clathrin adaptor that requires Arf1 for its membrane recruitment and which is known to be required for secretory granule biogenesis. Arl1 does not appear to be required for AP-1 recruitment in all tissues, suggesting that it is crucially required to enhance Arf1 activation at the trans-Golgi in particular tissues.
authors.affiliation: MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge CB2 0QH, UK.
authors.forename: Isabel L
authors.initials: IL
authors.lastname: Torres
authors.affiliation: MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge CB2 0QH, UK.
authors.forename: Cláudia
authors.initials: C
authors.lastname: Rosa-Ferreira
authors.affiliation: MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge CB2 0QH, UK sean@mrc-lmb.cam.ac.uk.
authors.forename: Sean
authors.initials: S
authors.lastname: Munro
mesh_terms: D020823:ADP-Ribosylation Factor 1 / Q000378:metabolism; D000818:Animals; D004330:Drosophila / Q000378:metabolism*; D029721:Drosophila Proteins / Q000378:metabolism*; D005260:Female; D008297:Male; D008565:Membrane Proteins / Q000378:metabolism*; D017434:Protein Structure, Tertiary; D021381:Protein Transport; D022142:Secretory Vesicles / Q000378:metabolism*; D018808:Transcription Factor AP-1 / Q000378:metabolism
chemical_list: C412166:Ari-1 protein, Drosophila; D029721:Drosophila Proteins; D008565:Membrane Proteins; D018808:Transcription Factor AP-1; D020823:ADP-Ribosylation Factor 1
keywords: Arf family; Secretory granule; Small G protein