The Planctomycetes-VerrucomicrobiaChlamydia (PVC) superphylum is a bacterial group whose members presentfeatures that are usually not found inbacteria but are more often associatedwith eukaryotes or archaea. One suchfeature is the presence of a complexendomembrane system inside the cell,which is sustained by proteins (such asgp4978) that display structural similarities to the eukaryotic membranecoat (MC) proteins involved in coatedvesicles (e.g. clathrin, COPII Sec31 andCOPI subunits alpha and beta0), as wellas in the nuclear pore complex (e.g.nup85 and nup133) [1]. We and othershave suggested that some of these bacterial features are related by verticaldescent to their archaeal or eukaryoticcounterparts, leading to alternativeeukaryogenesis hypotheses [2–6].
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