6ot0
From Proteopedia
Structure of human Smoothened-Gi complex
Structural highlights
Function[GBG2_HUMAN] Guanine nucleotide-binding proteins (G proteins) are involved as a modulator or transducer in various transmembrane signaling systems. The beta and gamma chains are required for the GTPase activity, for replacement of GDP by GTP, and for G protein-effector interaction (By similarity). [SMO_HUMAN] G protein-coupled receptor that probably associates with the patched protein (PTCH) to transduce the hedgehog's proteins signal. Binding of sonic hedgehog (SHH) to its receptor patched is thought to prevent normal inhibition by patched of smoothened (SMO). Required for the accumulation of KIF7 and GLI3 in the cilia.[1] [GBB1_HUMAN] Guanine nucleotide-binding proteins (G proteins) are involved as a modulator or transducer in various transmembrane signaling systems. The beta and gamma chains are required for the GTPase activity, for replacement of GDP by GTP, and for G protein-effector interaction.[2] [GNAI1_HUMAN] Guanine nucleotide-binding proteins (G proteins) are involved as modulators or transducers in various transmembrane signaling systems. The G(i) proteins are involved in hormonal regulation of adenylate cyclase: they inhibit the cyclase in response to beta-adrenergic stimuli. The inactive GDP-bound form prevents the association of RGS14 with centrosomes and is required for the translocation of RGS14 from the cytoplasm to the plasma membrane. May play a role in cell division.[3] [4] Publication Abstract from PubMedThe oncoprotein Smoothened (SMO), a G-protein-coupled receptor (GPCR) of the Frizzled-class (class-F), transduces the Hedgehog signal from the tumour suppressor Patched-1 (PTCH1) to the glioma-associated-oncogene (GLI) transcription factors, which activates the Hedgehog signalling pathway(1,2). It has remained unknown how PTCH1 modulates SMO, how SMO is stimulated to form a complex with heterotrimeric G proteins and whether G-protein coupling contributes to the activation of GLI proteins(3). Here we show that 24,25-epoxycholesterol, which we identify as an endogenous ligand of PTCH1, can stimulate Hedgehog signalling in cells and can trigger G-protein signalling via human SMO in vitro. We present a cryo-electron microscopy structure of human SMO bound to 24(S),25-epoxycholesterol and coupled to a heterotrimeric Gi protein. The structure reveals a ligand-binding site for 24(S),25-epoxycholesterol in the 7-transmembrane region, as well as a Gi-coupled activation mechanism of human SMO. Notably, the Gi protein presents a different arrangement from that of class-A GPCR-Gi complexes. Our work provides molecular insights into Hedgehog signal transduction and the activation of a class-F GPCR. Cryo-EM structure of oxysterol-bound human Smoothened coupled to a heterotrimeric Gi.,Qi X, Liu H, Thompson B, McDonald J, Zhang C, Li X Nature. 2019 Jun 5. pii: 10.1038/s41586-019-1286-0. doi:, 10.1038/s41586-019-1286-0. PMID:31168089[5] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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