The smoothened (SMO) receptor, a key signal transducer in the hedgehog signalling pathway, is responsible for the maintenance of normal embryonic development and is implicated in carcinogenesis. It is classified as a class frizzled (class F) G-protein-coupled receptor (GPCR), although the canonical hedgehog signalling pathway involves the GLI transcription factors and the sequence similarity with class A GPCRs is less than 10%. Here we report the crystal structure of the transmembrane domain of the human SMO receptor bound to the small-molecule antagonist LY2940680 at 2.5 Å resolution. Although the SMO receptor shares the seven-transmembrane helical fold, most of the conserved motifs for class A GPCRs are absent, and the structure reveals an unusually complex arrangement of long extracellular loops stabilized by four disulphide bonds. The ligand binds at the extracellular end of the seven-transmembrane-helix bundle and forms extensive contacts with the loops.
European journal of pharmacology 05/2015; 763. DOI:10.1016/j.ejphar.2015.05.012 · 2.53 Impact Factor
"The main technological advancements that enabled structural studies of GPCRs include (i) development of methods for heterologous expression in insect cells, (ii) discovery of a new method of membrane protein crystallization in lipidic cubic phase (Landau & Rosenbusch, 1996) and subsequent development of tools, instruments, and protocols for automation of crystallization and crystal detection, (iii) development of receptor stabilization technologies, including antibodies toward the intracellular side of GPCRs in Fab form (Rasmussen et al., 2007) and insertion of the T4 phage lysozyme domain (T4L) in the third intracellular (i3) loop (Cherezov et al., 2007; Rosenbaum et al., 2007), and (iv) development of microcrystallography. This toolbox for GPCR crystallization has rapidly expanded with (i) development of an alanine scanning mutagenesis approach enabling receptor stabilization in different functional states Serrano-Vega, Magnani, Shibata, & Tate, 2008; Warne et al., 2008), (ii) identification of other exogenous soluble fusion domains such as the thermostabilized apocytochrome b562RIL (BRIL) (Chun et al., 2012; Liu et al., 2012) and the rubredoxin (Tan et al., 427 The Ion Channel-Coupled Receptor Assay 2013), (iii) introduction of smaller camelid antibodies called nanobodies (Rasmussen, DeVree, et al., 2011a), and (iv) insertion of soluble domains in the N-terminus (Fenalti et al., 2014; Rasmussen, Choi, et al., 2011; Siu et al., 2013; Wang et al., 2013; Wu et al., 2014) and in the i2 loop (Hollenstein et al., 2013). Alone or in combination, these methods led to the structural determination of 25 other GPCRs from four different classes over the past 7 years. "
". Two Distinct Mechanisms of SMO-Mediated Resistance in BCCs (A) Position of the SMO variants within the SMO crystal structure showing their arrangement relative to an inhibitor (Wang et al., 2013) in TM3 "
Data provided are for informational purposes only. Although carefully collected, accuracy cannot be guaranteed. The impact factor represents a rough estimation of the journal's impact factor and does not reflect the actual current impact factor. Publisher conditions are provided by RoMEO. Differing provisions from the publisher's actual policy or licence agreement may be applicable.