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Journal of Molecular Evolution

, Volume 48, Issue 6, pp 770–778 | Cite as

Phylogenetic Analysis of Components of the Eukaryotic Vesicle Transport System Reveals a Common Origin of Adaptor Protein Complexes 1, 2, and 3 and the F Subcomplex of the Coatomer COPI

  • Kai  Schledzewski
  • Henner  Brinkmann
  • Ralf R.  Mendel

Abstract.

Eukaryotic vesicular transport requires the recognition of membranes through specific protein complexes. The heterotetrameric adaptor protein complexes 1, 2, and 3 (AP1/2/3) are composed of two large, one small, and one medium adaptin subunit. We isolated and characterized the cDNA for Arabidopsisγ-adaptin and performed a phylogenetic analysis of all adaptin subunits (proteins) in the context of all known homologous proteins. This analysis revealed (i) that the large subunits of AP1/2/3 are homologous and (ii) two subunits of the heptameric coatomer I (COPI) complex belong to this gene family. In addition, all small subunits and the aminoterminal domain of the medium subunits of the heterotetramers are homologous to each other; this also holds for two corresponding subunits of the COPI complex. AP1/2/3 and a substructure (heterotetrameric, F-COPI subcomplex) of the heptameric COPI had a common ancestral complex (called pre-F-COPI). Since all large and all small/medium subunits share sequence similarity, the ancestor of this complex is inferred to have been a heterodimer composed of one large and one small subunit. The situation encountered today is the result of successive rounds of coordinated gene duplications of both the large and the small/medium subunits, with F-COPI being the first that separated from the ancestral pre-F-COPI.

Key words: Adaptin — Clathrin — Endomembrane system — Eukaryotic evolution — Gene duplication — Multigene family — Phylogeny — Vesicular transport 

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Copyright information

© Springer-Verlag New York Inc. 1999

Authors and Affiliations

  • Kai  Schledzewski
    • 1
  • Henner  Brinkmann
    • 1
  • Ralf R.  Mendel
    • 1
  1. 1.Botanical Institute, Technical University of Braunschweig, Humboldtstrasse 1, 38106 Braunschweig, GermanyDE

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