The membrane-cytoskeleton linker ERMs (Ezrin, Radixin and Moesin) are structurally and functionally similar proteins. Merlin, a closely related paralogue, has extremely similar structure but seemingly different function. Whilst the ERMs have been implicated as structural elements of specialised and non specialised membrane structures, Merlin has been implicated as a critical regulator of at least one major signaling pathway (Hippo).
Merlin (and the ERMs) consist of a highly conserved FERM domain (a tri-lobed globular domain), an extended coiled-coil domain, and a self-interacting C-terminal domain (CTD). Merlin also contains a unique 19 amino acid tail at its N-terminus. The self-interaction of the CTD with the FERM domain causes an autoinhibitory effect in the ERMs, although curiously the same self-interaction in Merlin has been described as the ‘active state’ for certain processes. Ezrin has a critical phosphorylation site in the CTD at T567. This site has a proximal phosphorylation site on a highly conserved loop in the F3 lobe of the FERM domain at T235. Merlin contains highly conserved threonines in the same sites (T251, T576), and we are working to study the effect of mutating these. Additionally, we have hypothesized a direct interaction between an important structural/signaling protein Beta Catenin and Merlin that we have begun working on complexing and crystallizing for XRD experiments.
Straying away from in vitro molecular biology, we have begun working on imaging in vivo using Lattice Light Sheet Microscopy in retinal cells. Here we wish to investigate the different cellular functions of the paralogues an introduce hypothesized critical mutations to observe phenotypical changes to localization and cellular morphology.