Outerwear through the ages: evolutionary cell biology of vesicle coats

•Three well characterised coats have common features but different architectures.•Studies on diverse eukaryotes reveal ancient machinery, lineage-specific innovations.•This enabled discovery of new complexes in a clearly related set of coats (HTAC-CCs).•Asgard archea provide clues about ancestral coats.•Knowing the homology of vesicle coats informs both evolution and function.

Vesicular transport was key to the evolution of eukaryotes, and is essential for eukaryotic life today. All modern eukaryotes have a set of vesicle coat proteins, which couple cargo selection to vesicle budding in the secretory and endocytic pathways. Although these coats share common features (e.g. recruitment via small GTPases, β-propeller-α-solenoid proteins acting as scaffolds), the relationships between them are not always clear. Structural studies on the coats themselves, comparative genomics and cell biology in diverse eukaryotes, and the recent discovery of the Asgard archaea and their 'eukaryotic signature proteins' are helping us to piece together how coats may have evolved during the prokaryote-to-eukaryote transition.