title: An evolutionary perspective on eukaryotic membrane trafficking.
abstract: The eukaryotic cell is defined by a complex set of sub-cellular compartments that include endomembrane systems making up the exocytic and endocytic trafficking pathways. Current evidence suggests that both the function and communication between these compartments are regulated by distinct families of proteins that direct membrane fission, targeting and fusion. These families include coat protein complexes (CPCs) involved in vesicle formation/fission, Rab GTPases involved in vesicle targeting, and soluble N-ethyl-maleimide-sensitive factor attachment protein receptors (SNAREs) involved in vesicle fusion. The origins of these gene families and their individual contributions to the evolutionary specialization of the membrane architectures of lower and higher eukaryotes are now better understood with the advent of powerful phylogenetic, structural and systems biology tools. Herein, we provide a perspective that suggests that while the core CPC and SNARE machineries have diversified modestly in the course of eukaryotic evolution, the Rab GTPase family expanded substantially to emerge as a key driving force in endomembrane specialization. The Rab GTPases appear to have provided the foundation for the intricate membrane architectures ranging from those requisite for the distinct amoebic life cycle stage of uni-cellular organisms such as the parasitic protozoa to the highly specialized tissue and cell type-specific endomembranes of multi-cellular eukaryotes. We propose that Rab-centric interaction networks orchestrate the divergent activities of fission and fusion through their capacity to control the sequential assembly of protein complexes that mediate endomembrane structure and communication.
authors.affiliation: Department of Cell Biology, The Institute for Childhood and Neglected Disease, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, USA.
authors.forename: Cemal
authors.initials: C
authors.lastname: Gurkan
authors.forename: Atanas V
authors.initials: AV
authors.lastname: Koulov
authors.forename: William E
authors.initials: WE
authors.lastname: Balch
mesh_terms: D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D000818:Animals; D001692:Biological Transport; D002462:Cell Membrane / Q000378:metabolism*; D017124:Conserved Sequence; D005057:Eukaryotic Cells / Q000166:cytology* / Q000378:metabolism*; D019143:Evolution, Molecular; D020869:Gene Expression Profiling; D006801:Humans; D007425:Intracellular Membranes / Q000378:metabolism*; D008561:Membrane Fusion; D008954:Models, Biological; D008958:Models, Molecular; D008969:Molecular Sequence Data; D011487:Protein Conformation; D021381:Protein Transport; D050600:SNARE Proteins / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D020691:rab GTP-Binding Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism
chemical_list: D050600:SNARE Proteins; D020691:rab GTP-Binding Proteins