Phosphorylation of the vesicle-tethering protein p115 by a casein kinase II-like enzyme is required for Golgi reassembly from isolated mitotic fragments.
Coat protein I (COPI) transport vesicles can be tethered to Golgi membranes by a complex of fibrous, coiled-coil proteins comprising p115, Giantin and GM130. p115 has been postulated to act as a bridge, linking Giantin on the vesicle to GM130 on the Golgi membrane. Here we show that the acidic COOH terminus of p115 mediates binding to both GM130 and Giantin as well as linking the two together. Phosphorylation of serine 941 within this acidic domain enhances the binding as well as the link between them. Phosphorylation is mediated by casein kinase II (CKII) or a CKII-like kinase. Surprisingly, the highly conserved NH(2)-terminal head domain of p115 is not required for the NSF (N-ethylmaleimide-sensitive fusion protein)-catalyzed reassembly of cisternae from mitotic Golgi fragments in a cell-free system. However, the ability of p115 to link GM130 to Giantin and the phosphorylation of p115 at serine 941 are required for NSF-catalyzed cisternal regrowth. p115 phosphorylation may be required for the transition from COPI vesicle tethering to COPI vesicle docking, an event that involves the formation of trans-SNARE [corrected] (trans-soluble NSF attachment protein [SNAP] receptor) complexes.
Cell Biology Laboratory, Imperial Cancer Research Fund, London WC2A 3PX, United Kingdom.
A B
AB
Dirac-Svejstrup
J
J
Shorter
M G
MG
Waters
G
G
Warren
D000595:Amino Acid Sequence; D001324:Autoantigens; D001665:Binding Sites; D002352:Carrier Proteins / Q000378:metabolism*; D047390:Casein Kinase II; D006056:Golgi Apparatus / Q000502:physiology*; D000077614:Golgi Matrix Proteins; D008561:Membrane Fusion; D008565:Membrane Proteins / Q000378:metabolism*; D008938:Mitosis / Q000502:physiology*; D008969:Molecular Sequence Data; D052066:N-Ethylmaleimide-Sensitive Proteins; D010766:Phosphorylation; D011485:Protein Binding; D017346:Protein Serine-Threonine Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D012694:Serine / Q000378:metabolism; D033921:Vesicular Transport Proteins
D001324:Autoantigens; D002352:Carrier Proteins; D000077614:Golgi Matrix Proteins; C097741:Golgin subfamily A member 2; D008565:Membrane Proteins; D033921:Vesicular Transport Proteins; C087574:macrogolgin; C091580:vesicular transport factor p115; D012694:Serine; D047390:Casein Kinase II; D017346:Protein Serine-Threonine Kinases; D052066:N-Ethylmaleimide-Sensitive Proteins