Chemical complexity in the plasma membrane drives organization and dynamics at multiple time and length scales. The focus here will be on how this complex environment regulates specific protein-protein interactions for representative members of the receptor tyrosine kinase (RTK) family of membrane proteins. RTKs have a ligand-binding extra-cellular domain connected to an intra-cellular kinase domain through a single pass transmembrane helix. Assembly of RTKs into dimers, tetramers and higher order multimers is connected to receptor activation, which ultimately guides cellular function. To monitor RTK assembly in the live cell plasma membrane we use pulsed-interleaved excitation fluorescence cross-correlation spectroscopy (PIE-FCCS). PIE-FCCS monitors several physical parameters like mobility, concentration, proximity, and dimerization/multimerization. Recently we have shown a functional dependence between the degree of cross-correlation and the oligomerization state of the protein in the plasma membrane. This allows us to measure pairwise associations between RTK’s and determine how they are modulated by ligand activation and co-receptor associations. Recent data will be shown for two receptors, EphA2 and EGFR, which have adopt very different ligand-free and ligand-bound oligomerization states. With a series of point mutations we show that these assembly states regulate receptor function in cells and tumor growth in vivo.

Assembly of receptor tyrosine kinases in the plasma membrane regulates function at the protein, cell and organism levels

2019 Spring National Meeting

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