Other Membrane Proteins

Ephrin Receptor Tyrosine kinases collectively governs cell-cell recognition in the nervous, vascular, immune, and skeletal systems. Their dysregulation is strongly linked to the onset and progression of cancer. However, the development of therapeutics against Eph receptors remains at a relatively early stage due to a poor understanding of their structure and regulation. We are exploring the capability of cryo-EM to generate structures of this emerging class of drug targets. We have developed a cryo-EM research program on two members of Ephrin Receptor family, EphA10 and EphB6, leveraging on their unique features that can be exploited for drug discovery. Catalyst Therapeutics is an Industry partner for this project subtheme.

We have expanded our initial program on signalling receptors to include the study of Frizzled receptors (FZD), a class F GPCRs (overlapping with Theme 2), and their co-receptors ligands LRP5/6. The activation of FZD by Wnt proteins triggers a complex network of downstream signalling cascades. Wnt signalling is important in embryonic development and the maintenance of healthy tissue homeostasis in adults. Because of this, different members of Wnt signalling cascades are recognised as promising targets for the treatment of different human cancers.

Although several GPCR structures have been determined, the heterodimeric nature of the GABABR has hindered efforts for its structural elucidation. Cryo-EM is ideally suited to circumvent hurdles associated with recombinant protein production and heteromeric arrangement. Research around the investigation and development of cryo-EM techniques to enable structural resolution of the interactions. Knowledge obtained by the structural work will be used iteratively to computationally model and design novel compounds. We are currently in the process of producing GABABR protein constructs, characterising them using biophysical approaches, and acquiring initial cryo-EM data for structure determination.

Additional work is ongoing in characterisation of other membranes, including viral spike proteins, host cell receptors that mediate viral entry, amyloid proteins in Alzheimer’s disease, pore-forming toxins and ion channels, however, these are early phase projects within the Centre at this stage.

Many of our projects include collaborative Industry-partnered research, one of the key objectives of the Centre, the ARC ITTC scheme and the broader ARC Linkage program umbrella. Examples of established collaborative projects are noted below. Thermo Fisher Scientific is a broad partner within the Centre for technical innovation for membrane protein cryo-EM.

Other current (or in development) industry-partnered research projects:

• Astex Pharmaceuticals: Systematic investigation of factors driving resolution of receptors and low affinity ligand interactions.
• AstraZeneca: Methods for orphan receptor structure determination.
• Boehringer Ingelheim: Investigation of molecular mechanisms for biased agonism at incretin receptors. Structure determination of orphan GPCRs.
• Developing small molecules/ligands to interrogate Ephrin
• Receptor Pseudokinase family conformational dynamics.
• Dimerix: Structure determination of GPCR oligomers.