Measuring the Energetics of EphA3 Dimerization in Live Mammalian Cells

EphA3 is a member of the largest family of receptor tyrosine kinases, the Eph receptor family. Mutations in EphA3 are known to cause lung, colorectal and hepatocellular cancers. Unlike other subfamilies of RTKs, the Eph family receptors form clusters upon binding to their ligands. However, the interactions of EphA3 in the absence of ligand are not well characterized. We used two-photon microscopy in conjunction with spectral FRET to characterize the dimerization of EphA3 in the absence of ligand in HEK293T cells. We measured the dimerization propensity of EphA3 and compared it to the dimerization of the EphA2 receptor. Our results show that unliganded EphA3 dimers are more stable than unliganded EphA2 dimers.