assessing the relative stability of dimer interfaces in g protein-coupled receptors评估相对稳定的二聚体接口在g protein-coupled受体.pdf

Assessing the Relative Stability of Dimer Interfaces in G Protein-Coupled Receptors Jennifer M. Johnston., Hao Wang., Davide Provasi., Marta Filizola* Department of Structural and Chemical Biology, Mount Sinai School of Medicine, New York, New York, United States of America Abstract Considerable evidence has accumulated in recent years suggesting that G protein-coupled receptors (GPCRs) associate in the plasma membrane to form homo- and/or heteromers. Nevertheless, the stoichiometry, fraction and lifetime of such receptor complexes in living cells remain topics of intense debate. Motivated by experimental data suggesting differing stabilities for homomers of the cognate human b1- and b2-adrenergic receptors, we have carried out approximately 160 microseconds of biased molecular dynamics simulations to calculate the dimerization free energy of crystal structure-based models of these receptors, interacting at two interfaces that have often been implicated in GPCR association under physiological conditions. Specifically, results are presented for simulations of coarse-grained (MARTINI-based) and atomistic representations of each receptor, in homodimeric configurations with either transmembrane helices TM1/H8 or TM4/3 at the interface, in an explicit lipid bilayer. Our results support a definite contribution to the relative stability of GPCR dimers from both interface sequence and configuration. We conclude that b1- and b2-adrenergic receptor homodimers with TM1/ H8 at the interface are more stable than those involving TM4/3, and that this might be reconciled with experimental studies by considering a model of oligomerization in which more stable TM1 homodimers diffuse through the membrane, transiently interacting with other protomers at interfaces involving other TM helices. Citation: Johnston JM, Wang H,