Effect of FGFR3 Juxtamembrane Domain on FGFR3 Dimerization

Abstract

Receptor Tyrosine Kinases have four distinct domains: extracellular (EC), transmembrane (TM), juxtamembrane (JM), and catalytic (CAT). Receptor Tyrosine Kinase (RTK) dimerization is critical for RTK function, and disregulation of ligand-independent dimerization of RTKs is known to be the underlying cause for a number of human pathologies. Yet, the exact mechanism of RTK dimerization, and the roles of the four RTK domains in the dimerization process are unknown. To investigate the role of the juxtamembrane domain in ligand-independent homodimerization of RTKs, we are comparing the dimerization of two truncated FGFR3 constructs which both lack the catalytic domain, EC+TM+JM and EC+TM. We assess dimerization in single membrane-derived vesicles using the quantitative imaging FRET (QI-FRET) method [Li et al., 2008, Chen et al., 2010]. The results show that the juxtamembrane domain of FGFR3 increases the measured FRET efficiency and hence contributes to the energetics of lateral dimerization of the FGFR3 receptor. Li E,Placone J,Merzlyakov M, Hristova K (2008) Quantitative measurements of protein interactions in a crowded cellular environment.Anal Chem 80:5976-5985. Chen L, Novicky L, Merzlyakov M, Hristov T, Hristova K (2010) Measuring the energetics of membrane protein dimerization in mammalian membranes. J Am Chem Soc 17;132(10):3628-35.