A novel adaptor-related protein complex.
Coat proteins are required for the budding of the transport vesicles that mediate membrane traffic pathways, but for many pathways such proteins pathways, but for many pathways such proteins have not yet been identified. We have raised antibodies against p47, a homologue of the medium chains of the adaptor complexes of clathrin-coated vesicles (Pevsner, J., W. Volknandt, B.R. Wong, and R.H. Scheller. 1994. Gene (Amst.). 146:279-283), to determine whether this protein might be a component of a new type of coat. p47 coimmunoprecipitates with three other proteins: two unknown proteins of 160 and 25 kD, and beta-NAP, a homologue of the beta/beta'-adaptins, indicating that it is a subunit of an adaptor-like heterotetrameric complex. However, p47 is not enriched in preparations of clathrin-coated vesicles. Recruitment of the p47-containing complex onto cell membranes is stimulated by GTP gamma S and blocked by brefeldin A, indicating that, like other coat proteins, its membrane association is regulated by an ARF. The newly recruited complex is localized to non-clathrin-coated buds and vesicles associated with the TGN. Endogenous complex in primary cultures of neuronal cells is also localized to the TGN, and in addition, some complex is associated with the plasma membrane. These results indicate that the complex is a component of a novel type of coat that facilitates the budding of vesicles from the TGN, possibly for transporting newly synthesized proteins to the plasma membrane.
Simpson
F
F
Department of Clinical Biochemistry, University of Cambridge, United Kingdom.
Bright
N A
NA
West
M A
MA
Newman
L S
LS
Darnell
R B
RB
Robinson
M S
MS
D033963:Adaptor Protein Complex 3; D033966:Adaptor Protein Complex beta Subunits; D000818:Animals; D001483:Base Sequence; D002460:Cell Line; D002462:Cell Membrane; D002966:Clathrin / Q000378:metabolism; D053487:DEAD-box RNA Helicases; D017931:DNA Primers; D007158:Immunologic Techniques; D008969:Molecular Sequence Data; D009419:Nerve Tissue Proteins / Q000378:metabolism*; D009687:Nuclear Proteins / Q000378:metabolism*; D016716:PC12 Cells; D010750:Phosphoproteins / Q000378:metabolism*; D011817:Rabbits; D051381:Rats
C095597:AP3B2 protein, human; D033963:Adaptor Protein Complex 3; D033966:Adaptor Protein Complex beta Subunits; D002966:Clathrin; D017931:DNA Primers; D009419:Nerve Tissue Proteins; D009687:Nuclear Proteins; D010750:Phosphoproteins; C075446:Ddx39b protein, rat; D053487:DEAD-box RNA Helicases