The structure of the TRAPP subunit TPC6 suggests a model for a TRAPP subcomplex.
The TRAPP (transport protein particle) complexes are tethering complexes that have an important role at the different steps of vesicle transport. Recently, the crystal structures of the TRAPP subunits SEDL and BET3 have been determined, and we present here the 1.7 Angstroms crystal structure of human TPC6, a third TRAPP subunit. The protein adopts an alpha/beta-plait topology and forms a dimer. In spite of low sequence similarity, the structure of TPC6 strikingly resembles that of BET3. The similarity is especially prominent at the dimerization interfaces of the proteins. This suggests heterodimerization of TPC6 and BET3, which is shown by in vitro and in vivo association studies. Together with TPC5, another TRAPP subunit, TPC6 and BET3 are supposed to constitute a family of paralogous proteins with closely similar three-dimensional structures but little sequence similarity among its members.
Kümmel
Daniel
D
Max-Delbrück Center for Molecular Medicine, Berlin, Germany.
Müller
Jürgen J
JJ
Roske
Yvette
Y
Misselwitz
Rolf
R
Büssow
Konrad
K
Heinemann
Udo
U
D000595:Amino Acid Sequence; D015153:Blotting, Western; D002942:Circular Dichroism; D018360:Crystallography, X-Ray; D018076:DNA, Complementary / Q000378:metabolism; D019281:Dimerization; D006056:Golgi Apparatus / Q000378:metabolism; D006801:Humans; D008565:Membrane Proteins / Q000737:chemistry* / Q000378:metabolism; D008958:Models, Molecular; D008969:Molecular Sequence Data; D005810:Multigene Family; D011485:Protein Binding; D011487:Protein Conformation; D017510:Protein Folding; D017433:Protein Structure, Secondary; D011994:Recombinant Proteins / Q000737:chemistry; D033921:Vesicular Transport Proteins / Q000737:chemistry* / Q000378:metabolism
D018076:DNA, Complementary; D008565:Membrane Proteins; D011994:Recombinant Proteins; C503571:TRAPPC3 protein, human; C506760:TRAPPC5 protein, human; C506759:TRAPPC6B protein, human; D033921:Vesicular Transport Proteins; C406327:transport protein particle, TRAPP