The Role of Asp578 in Maintaining the Inactive Conformation of the Human Lutropin/Choriogonadotropin Receptor

Kosugi, Shinji; Mori, Toru; Shenker, Andrew

doi:10.1074/jbc.271.50.31813

Cited by 86 publications

(90 citation statements)

References 30 publications

(32 reference statements)

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“…with Q n less than 0.5, were identified in intracellular loop 3, although Ala-scanning is not yet complete of that region. D564 replacements, as expected (Kosugi et al, 1998;Schulz et al, 1999), gave constitutive activation with replacements other than Glu. Other experimental approaches are now being taken to investigate LHR-Gα coupling, and these will be incorporated into molecular dynamics simulations and docking studies to obtain a better understanding of this important aspect of LHR signaling.…”

Section: Mode Of Activated Lhr Coupling To Gαsupporting

confidence: 67%

A functional transmembrane complex: The luteinizing hormone receptor with bound ligand and G protein

Puett

DeMars

et al. 2007

Molecular and Cellular Endocrinology

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The luteinizing hormone receptor (LHR) is one of eight members in a cluster of the rhodopsin family of the large G protein-coupled receptor (GPCR) superfamily that contains some 800-900 genes in the human genome. LHR, along with its paralogons, follicle stimulating hormone receptor (FSHR) and thyroid stimulating hormone receptor, form one of the three classes in this cluster; the two other classes contain the relaxin-binding GPCRs and orphan GPCRs. These GPCRs are characterized by a relatively large ectodomain (ECD) containing leucine-rich-repeats (LRRs); in the class of glycoprotein hormone receptors, the LRR region is capped by N-terminal and C-terminal cysteinerich regions. Binding of human chorionic gonadotropin (hCG) or luteinizing hormone to the LHR-ECD triggers a conformational change of the transmembrane region of the receptor facilitating binding and activation of Gs, followed by effector enzyme activation and subsequent intracellular signaling. Viewing LHR as a transmembrane anchoring protein that sequentially binds hCG and Gs to give the hCG-LHR-Gs complex, numerous interactions and conformational changes must be considered. There is, unfortunately, a paucity of structural data on LHR, but crystal structures exist for hCG, the homologous FSH-FSHR-ECD (N-terminal fragment) complex, rhodopsin (in the inactive state), an active form of Gαs (transducin), and the βγ heterodimer. Using a combined experimental (site-directed mutagenesis followed by characterization in transfected cells) and computational (homology modeling and molecular dynamics simulations) approach, good working models are being developed for the protein-protein interaction faces and, in some cases, the ensuing conformational changes induced by complex formation. hCG binding to the LHR-ECD appears to involve several LRRs; LHR activation can be described in terms of disrupting a network of H-bonds in the cytosolic halves of helices 1-3, 6, and 7; and binding of LHR to Gs involves, in large part, intracellular loop 2 binding, presumably to Gsα at its C-terminus. Major gaps exist in our understanding at the molecular level of the six-polypeptide chain complex, hCG-LHR-Gs, but considerable progress has been made in the past few years.

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Section: Mode Of Activated Lhr Coupling To Gαsupporting

confidence: 67%

A functional transmembrane complex: The luteinizing hormone receptor with bound ligand and G protein

Puett

DeMars

et al. 2007

Molecular and Cellular Endocrinology

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“…This is also substantially (ϳ9-fold) higher than the normal basal cAMP level. This is a significant difference when compared with the maximum cAMP level of activating mutant LHRs, which is 5-8-fold greater than the normal cAMP basal level (41).…”

Section: Discussionmentioning

confidence: 97%

Two Defective Heterozygous Luteinizing Hormone Receptors Can Rescue Hormone Action

Lee

Ryu

et al. 2002

Journal of Biological Chemistry

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Luteinizing hormone receptor is a G protein-coupled receptor and consists of two halves: the N-terminal extracellular half (exodomain) and C-terminal membraneassociated half (endodomain). Hormone binds to the exodomain, and the resulting hormone-exodomain complex modulates the endodomain to generate signals. There are mutations that impair either hormone binding or signal generation. We report that the coexpression of a binding defective mutant and a signal-defective mutant rescues signal generation to produce cAMP. This rescue requires both types of mutant receptors and is dependent on the human chorionic gonadotropin dose, the surface concentration of mutant receptors, and the amino acid position of mutations. Furthermore, random collisions among mutant receptors are not involved in the rescue. Our observations provide new insights into the mechanisms of the functional and structural relationship of the exo-and endodomain, signal transduction, and receptor genetics, in particular for defective heterozygotes.

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“…The very low surface expression (1/5 or less) of the mutant receptors may be responsible in Del(613±621) and Del(658±661) (7,8,30). However, L512R retained 52% B max which was similar to or higher than that of the WT(5) transfectant ( Table 1) that showed a good response to TSH (Fig.…”

Section: European Journal Of Endocrinology (2000) 143mentioning

confidence: 98%

A novel activating mutation in the thyrotropin receptor gene in an autonomously functioning thyroid nodule developed by a Japanese patient

Kosugi

Hai²,

Okamoto³

et al. 2000

European Journal of Endocrinology

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Objective: A number of activating mutations of the thyrotropin receptor (TSHR) have been found in autonomously functioning thyroid nodules (AFTNs) in European patients. We aimed to study TSHR mutation in AFTNs in Japanese patients because no TSHR activating mutation has been found by previous incomplete studies. Design: A typical AFTN developed in a 69-year-old Japanese woman was studied. Methods: The entire exon 10 of the TSHR cDNA was sequenced. Functional studies were done by sitedirected mutagenesis and transfection of a mutant construct into COS-7 cells. Results: We identi®ed a novel heterozygous TSHR gene mutation, Leu512!Arg (L512R; CTG!CCG), from the AFTN. The mutation was not detected in the adjacent normal thyroid tissue. COS-7 cells transfected with L512R mutant TSHR expression vector exhibited a 3.3-fold increase in basal cAMP level compared with that of cells transfected with wild-type TSHR DNA, con®rming that the mutation was the direct cause of the AFTN.TSHR activating mutations involving the third transmembrane helix reported to date are S505R/N and V509A as well as L512R. An in vitro site-directed mutagenesis study encompassing residues 505± 513 revealed that mutations involving residues other than these three did not show constitutive activation. Conclusion: This is the ®rst TSHR activating mutation found in a Japanese patient, although true prevalence of TSHR activating mutations in AFTNs developed in Japanese patients remains to be elucidated. In addition, functional studies suggested that amino acid residues in the third transmembrane helix maintaining inactive conformation of the TSHR seem to be located on the same surface of the a-helix, possibly making interhelical bonds with another helix.

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The Role of Asp578 in Maintaining the Inactive Conformation of the Human Lutropin/Choriogonadotropin Receptor

Cited by 86 publications

References 30 publications

A functional transmembrane complex: The luteinizing hormone receptor with bound ligand and G protein

A functional transmembrane complex: The luteinizing hormone receptor with bound ligand and G protein

Two Defective Heterozygous Luteinizing Hormone Receptors Can Rescue Hormone Action

A novel activating mutation in the thyrotropin receptor gene in an autonomously functioning thyroid nodule developed by a Japanese patient

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