Model of Human Chorionic Gonadotropin and Lutropin Receptor Interaction That Explains Signal Transduction of the Glycoprotein Hormones

Moyle, William R.; Campbell, R. Keith; Rao, S.N. Venkateswara; Ayad, Nagi G.; Bernard, Michael P.; Han, Yi; Wang, Yanhong

doi:10.1074/jbc.270.34.20020

Cited by 119 publications

(96 citation statements)

References 46 publications

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“…Interactions among these domains have been previously proposed to explain signal transduction by the glycoprotein hormone receptors (21,45). The data presented here clearly show that such interactions are equally important in determining the fate of the agonist-activated receptor.…”

Section: Discussionsupporting

confidence: 52%

The Rate of Internalization of the Gonadotropin Receptors Is Greatly Affected by the Origin of the Extracellular Domain

Nakamura

Liu

Ascoli

1999

Journal of Biological Chemistry

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Previous results from this laboratory have shown that human kidney (293) cells transfected with the rat follitropin receptor (rFSHR) internalize agonist (i.e. human follitropin, hFSH) at a rate similar to that of other agonist-G protein-coupled receptor complexes while 293 cells transfected with the rat lutropin/choriogonadotropin receptor (rLHR) internalize agonist (human choriogonadotropin, hCG) at a rate that is about 1 order of magnitude slower. Taking advantage of this difference and the high degree of homology between the rLHR and rFSHR, we have now used chimeras of these two receptors to begin to delineate structural features that influence their internalization. Analysis of six chimeras that exchanged only the transmembrane domains (designated FLF and LFL), only the COOH-terminal domains (FFL or LLF) or both domains (FLL or LFF) show that the origin of the extracellular domain is at least as important, if not more, than the origin of the transmembrane and COOH-terminal domains in determining the rate of internalizationof the gonadotropin receptors. Thus, the rates of internalization of agonist internalization mediated by FFL, FLF, and FLL more closely resemble rFSHR than rLHR, while the rates of agonist internalization mediated by LLF, LFL, and LFF more closely resemble rLHR than rFSHR.The importance of the extracellular domain was also evident even upon overexpression of arrestin-3, a protein that enhances the rate of internalization of the wild-type receptors and chimeras by binding to their intracellular regions.

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Section: Discussionsupporting

confidence: 52%

The Rate of Internalization of the Gonadotropin Receptors Is Greatly Affected by the Origin of the Extracellular Domain

Nakamura

Liu

Ascoli

1999

Journal of Biological Chemistry

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“…Based on the pseudo-LRR nature of much of the LHR-ECD and the structure of the LRR protein, ribonuclease inhibitor (Kobe and Disenhofer, 1993), as a template, several laboratories proposed models for the LHR-ECD with 9-14 LRRs (Moyle et al, 1995;Kajava et al, 1995;Jiang et al, 1995;Bhowmick et al, 1996;Couture et al, 1996;Song et al, 2001a), the former of which now appears to be more accurate. Using the threading program PROSPECT (Kim et al, 2003) and the SCOP40 database (Chandonia et al, 2004), we comparatively modeled the LHR-ECD prior to the publication of the FSH-FSHR-ECD complex.…”

Section: The Lhr-ecd: Structure and Hormone Bindingmentioning

confidence: 99%

“…Moyle et al, 1995Moyle et al, , 2004Moyle et al, , 2005Fan and Hendrickson, 2005a,b;Karges et al 2005 for the most recent models); however, to date there is no general consensus on this important aspect of receptor activation. Indeed, controversy remains over whether the ECD restrains the transmembrane portion of LHR in an inactive form, a restraint that is removed concomitant with ligand binding, or whether the transmembrane portion remains in an inactive state unless activated by the hCG-ECD complex.…”

Section: Mode Of Communication Of the Hcg-lhr-ecd Complex With The Trmentioning

confidence: 99%

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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“…The sources of hCG and antibodies used in these studies have been described (13)(14)(15). We radioiodinated hCG and antibody B110 using an IODO-GEN procedure (16).…”

Section: Methodsmentioning

confidence: 99%

Only a Portion of the Small Seatbelt Loop in Human Choriogonadotropin Appears Capable of Contacting the Lutropin Receptor

Bernard

Lin

Cao

et al. 2004

Journal of Biological Chemistry

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Twenty residues of the human choriogonadotropin (hCG) ␤-subunit that are wrapped around ␣-subunit loop 2 like a "seatbelt" stabilize the heterodimer and enable the hormone to distinguish lutropin (LHR), follitropin, and thyrotropin receptors. The N-terminal portion of the seatbelt contains a small disulfide-stabilized loop needed for heterodimer assembly and is thought to mediate hCG-LHR interactions. To test the latter notion, we compared the LHR binding and signal transduction activities of hCG analogs in which the ␣-subunit C terminus (␣CT) was cross-linked to residues in the small seatbelt loop. Analogs having an intersubunit disulfide between a cysteine in place of ␣CT residue ␣Ser-92 and cysteines substituted for loop residues ␤Arg-94, ␤Arg-95, or ␤Ser-96 had high activities in LHR binding and signaling assays despite the fact that both portions of the hormone are thought to be essential for hCG activity. Use of a larger probe blocked hormone activity when the ␣CT was crosslinked to cysteines in place of residues ␤Arg-95 and ␤Asp-99, but not to cysteines in place of residues ␤Arg-94, ␤Ser-96, or ␤Thr-97. This suggested that the side chains of residues ␤Arg-95 and ␤Asp-99, which face in the same outward direction from the heterodimer, are nearer than the others to the LHR interface. The finding that residue 95 can be cross-linked to small ␣CT probes without eliminating hormone activity indicates its side chain does not participate in essential LHR contacts. We suggest that contacts between the small seatbelt loop and the LHR, if any, involve its backbone atoms and possibly the side chain of residue ␤Asp-99.The crystal structure of hCG 1 revealed that 20 residues of its ␤-subunit surround loop ␣2 like a "seatbelt" (1, 2). The seatbelt has a key role in the stability of the heterodimer; elimination of the disulfide that "latches" its C-terminal end to ␤Cys-26 in the subunit core disrupts heterodimer formation (3). Thus, glycoprotein hormones differ from most other heterodimeric proteins, which are stabilized by hydrophobic contacts or intersubunit disulfides. Whereas the evolutionary advantages of this unusual structural arrangement remain unknown, it may have facilitated the co-evolution of ligand-receptor pairs by permitting point mutations to alter the conformation of the heterodimer and thereby modulate its biological activity (4 -6).The seatbelt is divided into two regions that differ in their influence on the activities of lutropins, follitropins, and thyrotropins. Its N-terminal half contains a small disulfide-stabilized loop that has an important role in heterodimer assembly (7-9). Because a portion of this loop participates in hydrogen bonds with ␣-subunit loop 2 (1, 2, 10), mutations that affected its conformation or the stability of these hydrogen bonds would be expected to alter the positions of the subunits in the heterodimer. The seatbelt loop contains positively charged residues in mammalian lutropins and negatively charged residues in mammalian follitropins and thyrotropins. This led to the sp...

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Model of Human Chorionic Gonadotropin and Lutropin Receptor Interaction That Explains Signal Transduction of the Glycoprotein Hormones

Cited by 119 publications

References 46 publications

The Rate of Internalization of the Gonadotropin Receptors Is Greatly Affected by the Origin of the Extracellular Domain

The Rate of Internalization of the Gonadotropin Receptors Is Greatly Affected by the Origin of the Extracellular Domain

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

Only a Portion of the Small Seatbelt Loop in Human Choriogonadotropin Appears Capable of Contacting the Lutropin Receptor

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