Evidence that Golgi structure depends on a p115 activity that is independent of the vesicle tether components giantin and GM130.
Inhibition of the putative coatomer protein I (COPI) vesicle tethering complex, giantin-p115-GM130, may contribute to mitotic Golgi breakdown. However, neither this, nor the role of the giantin-p115-GM130 complex in the maintenance of Golgi structure has been demonstrated in vivo. Therefore, we generated antibodies directed against the mapped binding sites in each protein of the complex and injected these into mammalian tissue culture cells. Surprisingly, the injected anti-p115 and antigiantin antibodies caused proteasome-mediated degradation of the corresponding antigens. Reduction of p115 levels below detection led to COPI-dependent Golgi fragmentation and apparent accumulation of Golgi-derived vesicles. In contrast, neither reduction of giantin below detectable levels, nor inhibition of p115 binding to GM130, had any detectable effect on Golgi structure or Golgi reassembly after cell division or brefeldin A washout. These observations indicate that inhibition of p115 can induce a mitotic-like Golgi disassembly, but its essential role in Golgi structure is independent of its Golgi-localized binding partners giantin and GM130.
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Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, PA 15213, USA.
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D000906:Antibodies / Q000008:administration & dosage / Q000494:pharmacology; D001324:Autoantigens; D002352:Carrier Proteins / Q000276:immunology / Q000502:physiology*; D020755:Coat Protein Complex I / Q000502:physiology; D003546:Cysteine Endopeptidases / Q000502:physiology; D022162:Cytoplasmic Vesicles / Q000737:chemistry; D006056:Golgi Apparatus / Q000648:ultrastructure*; D000077614:Golgi Matrix Proteins; D006367:HeLa Cells; D006801:Humans; D046911:Macromolecular Substances; D008565:Membrane Proteins / Q000276:immunology / Q000502:physiology*; D008845:Microinjections; D008938:Mitosis; D009097:Multienzyme Complexes / Q000502:physiology; D046988:Proteasome Endopeptidase Complex; D033921:Vesicular Transport Proteins
D000906:Antibodies; D001324:Autoantigens; D002352:Carrier Proteins; D020755:Coat Protein Complex I; D000077614:Golgi Matrix Proteins; C097741:Golgin subfamily A member 2; D046911:Macromolecular Substances; D008565:Membrane Proteins; D009097:Multienzyme Complexes; D033921:Vesicular Transport Proteins; C087574:macrogolgin; C091580:vesicular transport factor p115; D003546:Cysteine Endopeptidases; D046988:Proteasome Endopeptidase Complex