Molecular mechanisms involved in transport vesicle coat formation
Transmembrane proteins are moved between organelles in transport vesicles. Once cargo has been sorted into a forming vesicle, the vesicle buds from the donor membrane and is then transported to and fuses with the target membrane. Post-Golgi transport is mainly mediated by clathrin-coated vesicles (CCVs), whose coats are composed of an outer clathrin scaffold linked to the membrane by clathrin adaptors including AP complexes, GGAs, epsins and ARH. We use a combination of X-ray crystallography, biochemistry and cell biology to study the structure and function of components of vesicle coats.
Clathrin adaptors have folded domains that bind to membrane phospholipid headgroups and in some cases simultaneously bind to transmembrane cargo thereby selecting the cargo for incorporation into a CCV. The extended, flexible regions of the adaptors that connect the folded domains contain multiple short motifs, which bind to clathrin and the appendages of APs and GGAs. These latter interactions help to recruit lower abundancy clathrin adaptors, such as the epsins and ARH, and non clathrin-binding accessory proteins into forming CCVs. Along with phosphorylation/dephosphorylation events, these interactions drive the assembly and disassembly of the CCVs coat. The folded domains of clathrin adaptors recognise short, transplantable, linear motifs that are found on the cytoplasmic portions of many cargoes such as YxxF and [DE]xxxLL (that bind AP complexes) and FxNPxY (that bind ARH) but also highly protein specific, fold-dependent, surface epitopes on a single cargo such as those found on the SNARE proteins, which mediate the fusion of vesicles with their target membranes. Our current work focuses on the structure, interactions and regulation of AP complexes (collaborations with Phil Evans (LMB) and Stefan Honing (Cologne)) and how SNAREs and other non-motif containing cargo interact with CCV components (collaborations with Margaret Robinson and Paul Luzio)
Group members
- Melissa Edeling
- Bernard Kelly
- Sharon Miller
Funding
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