1
|
Cosowsky L, Lin W, Han Y, Bernard MP, Campbell RK, Moyle WR. Influence of subunit interactions on lutropin specificity. Implications for studies of glycoprotein hormone function. J Biol Chem 1997; 272:3309-14. [PMID: 9013570 DOI: 10.1074/jbc.272.6.3309] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Bovine lutropin (bLH) and human chorionic gonadotropin (hCG) are heterodimeric glycoprotein hormones required for reproduction. Both bind rat LH receptors (rLHRs), but hCG binds human LH receptors (hLHRs) 1000-10,000 fold better than bLH. We tested the premise that this difference in affinity could be used to identify lutropin receptor contacts. Heterodimers containing hCG/bLH alpha- or beta-subunit chimeras that bound hLHR like hCG (or bLH) were expected to have hCG (or bLH) residues at the receptor contact sites. Analogs containing one subunit derived from hCG bound hLHR much more like hCG than bLH, indicating that each bLH subunit contains all the residues sufficient for high affinity hLHR binding. Indeed, the presence of bovine alpha-subunit residues increased the activities of some hCG analogs. The low hLHR activity of bLH was due primarily to an interaction between its alpha-subunit and beta-subunit residue Leu95. Leu95 does not appear to contact the hLHR since it did not influence the hLHR activity of heterodimers containing human alpha-subunit. These observations show that interactions within and between the subunits can significantly influence the activities of lutropins, thereby confounding efforts to identify ligand residues that contact these receptors.
Collapse
Affiliation(s)
- L Cosowsky
- Department of Obstetrics and Gynecology, Robert Wood Johnson (Rutgers) Medical School, Piscataway, New Jersey 08854, USA
| | | | | | | | | | | |
Collapse
|
2
|
Ji I, Pan YN, Lee YM, Phang T, Ji TH. Receptor binding dependent structural changes in human choriogonadotropin: photochemical inter-subunit crosslinking. Endocrine 1995; 3:907-11. [PMID: 21153219 DOI: 10.1007/bf02738896] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/28/1995] [Accepted: 09/26/1995] [Indexed: 11/24/2022]
Abstract
Activation of surface receptors is thought to occur in multiple transient steps with conformational adjustments of hormones and receptors beginning from the initial hormone-receptor contact. In this study, we have established a sensitive photochemical crosslinking method to detect structural change of hCG upon receptor binding. hCG consists of an α subunit and a β subunit. Free α subunit was derivatized with photosensitive reagents and reassociated with unmodified β subunit. Reassociated hCG αβ dimer was capable of high affinity receptor binding and activation. The reagents attached to the α subunit were capable of crosslinking the α subunit to the β subunit. However, the extent of inter-subunit cross-linking in solution was two-three fold greater than inter-subunit crosslinking after hCG bound to the receptor. This difference indicates a novel structural change at the subunit interface in response to hCG binding to the receptor. Although highly unlikely, other microenvironmental factors might have interfered with the crosslinking efficiency without impacting the structure of hCG. This study lays the ground work to precisely define the location and nature of the change. Such information will be crucial for the understanding of the molecular mechanism of the hormone-receptor interaction and receptor activation.
Collapse
Affiliation(s)
- I Ji
- Department of Molecular Biology, University of Wyoming, 82071-3944, Laramie, V/yoming, USA
| | | | | | | | | |
Collapse
|
3
|
Moyle WR, Campbell RK, Rao SN, Ayad NG, Bernard MP, Han Y, Wang Y. Model of human chorionic gonadotropin and lutropin receptor interaction that explains signal transduction of the glycoprotein hormones. J Biol Chem 1995; 270:20020-31. [PMID: 7650020 DOI: 10.1074/jbc.270.34.20020] [Citation(s) in RCA: 103] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
The goal of these studies was to devise a model that explains how human chorionic gonadotropin (hCG) interacts with lutropin (LH) receptors to elicit a hormone signal. Here we show that alpha-subunit residues near the N terminus, the exposed surface of the cysteine knot, and portions of the first and third loops most distant from the beta-subunit interface were recognized by antibodies that bound to hCG-receptor complexes. These observations were combined with similar data obtained for the beta-subunit (Cosowsky, L., Rao, S.N.V., Macdonald, G.J., Papkoff, H., Campbell, R.K., and Moyle, W.R. (1995) J. Biol. Chem. 270, 20011-20019), information on residues of hCG that can be changed without disrupting hormone function, the crystal structure of deglycosylated hCG, and the crystal structure of a leucine-repeat protein to devise a model of hCG-receptor interaction. This model suggest that the extracellular domain of the LH receptor is "U-" or "J"-shaped and makes several contacts with the transmembrane domain. High affinity hormone binding results from interactions between residues in the curved portion of the extracellular domain of the receptor and the groove in the hormone formed by the apposition of the second alpha-subunit loop and the first and third beta-subunit loops. Most of the remainder of the hormone is found in the large space between the arms of the extracellular domain and makes few, if any, additional specific contacts with the receptor needed for high affinity binding. Signal transduction is caused by steric or other influences of the hormone on the distance between the arms of the extracellular domain, an effect augmented by the oligosaccharides. Because the extracellular domain is coupled at multiple sites to the transmembrane domain, the change in conformation of the extracellular domain is relayed to the transmembrane domain and subsequently to the cytoplasmic surface of the plasma membrane. While the model does not require the hormone to contact the transmembrane domain to initiate signal transduction, small portions of both subunits may be near the transmembrane domain and assist in initiating the hormonal signal. This is the first model that is consistent with all known information on the activity of the gonadotropins including the amounts of the hormone that are exposed in the hormone-receptor complex, the apparent lack of specific contacts between much of the hormone and the receptor, and the roles of the oligosaccharides in signal transduction.(ABSTRACT TRUNCATED AT 400 WORDS)
Collapse
Affiliation(s)
- W R Moyle
- Department of Obstetrics/Gynecology, Robert Wood Johnson (Rutgers) Medical School, Piscataway, New Jersey 08854, USA
| | | | | | | | | | | | | |
Collapse
|
4
|
Fairlie WD, Stanton PG, Hearn MTW. Delineation of Tyrosine-Containing Epitopes within the beta Subunit of Bovine Thyrotropin. ACTA ACUST UNITED AC 1995. [DOI: 10.1111/j.1432-1033.1995.tb20273.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
|
5
|
Hayashi H, Hayashi T, Hanaoka Y. Amphibian lutropin from the bullfrog Rana catesbeiana. Complete amino acid sequence of the beta subunit. EUROPEAN JOURNAL OF BIOCHEMISTRY 1992; 205:105-10. [PMID: 1555571 DOI: 10.1111/j.1432-1033.1992.tb16756.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The amino acid sequence of lutropin (LH) beta subunit of an amphibian, the bullfrog Rana catesbeiana, has been determined. The primary structure was determined by sequencing the intact protein (residues 1-44) and peptides originated by cyanogen bromide cleavage and lysyl endopeptidase digestion. 12 cysteine residues are conserved in the bullfrog and mammalian LH beta subunit. One sugar-chain-binding site at Asn-8 is also conserved in the bullfrog and in all mammals except humans. This glycoprotein is composed of 112 amino acid residues with a molecular mass of 12675 Da, considering the six cystine bridges and excepting the sugar chain. The bullfrog beta subunit has approximately 50% sequence identity with that of mammals and with the fish gonadotropin beta subunit, and about 40% with bullfrog follicle-stimulating hormone beta subunit.
Collapse
Affiliation(s)
- H Hayashi
- Institute of Endocrinology, Gunma University, Maebashi, Japan
| | | | | |
Collapse
|
6
|
Immunochemical mapping of antigenic regions on the human thyrotropin beta-subunit by antipeptide antibodies. J Biol Chem 1991. [DOI: 10.1016/s0021-9258(18)54988-7] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
|
7
|
Reed D, Ryan R, McCormick D. Residues in the alpha subunit of human choriotropin that are important for interaction with the lutropin receptor. J Biol Chem 1991. [DOI: 10.1016/s0021-9258(18)98675-8] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
|
8
|
Santa-Coloma TA, Reichert LE. Determination of alpha-subunit contact regions of human follicle-stimulating hormone beta-subunit using synthetic peptides. J Biol Chem 1991. [DOI: 10.1016/s0021-9258(18)49910-3] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
|
9
|
Bidart JM, Troalen F, Ghillani P, Rouas N, Razafindratsita A, Bohuon C, Bellet D. Peptide immunogen mimicry of a protein-specific structural epitope on human choriogonadotropin. Science 1990; 248:736-9. [PMID: 1692160 DOI: 10.1126/science.1692160] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
It is a challenge to construct synthetic immunogens that elicit antibodies (Abs) both directed to conformational epitopes and specific for a complex protein like human choriogonadotropin (hCG). A monoclonal antibody specific for hCG bound to regions around Lys45 of the alpha subunit (hCG alpha) and Asp112 of the beta subunit (hCG beta). A peptide comprising residues 46 to 55 of hCG alpha and residues 106 to 116 of hCG beta elicited Abs in rabbits that were directed to a discontinuous epitope and were specific for hCG. These Abs inhibited the binding of hCG to its receptor. Thus, a synthetic immunogen can mimic a conformational-specific epitope and can be useful for vaccine development.
Collapse
Affiliation(s)
- J M Bidart
- Département de Biologie Clinique, Institut Gustave-Roussy, Villejuif, France
| | | | | | | | | | | | | |
Collapse
|
10
|
Localization of residues that confer antibody binding specificity using human chorionic gonadotropin/luteinizing hormone beta subunit chimeras and mutants. J Biol Chem 1990. [DOI: 10.1016/s0021-9258(19)38918-5] [Citation(s) in RCA: 58] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
|
11
|
Kato YP, Silver FH. Formation of continuous collagen fibres: evaluation of biocompatibility and mechanical properties. Biomaterials 1990; 11:169-75. [PMID: 2350553 DOI: 10.1016/0142-9612(90)90150-o] [Citation(s) in RCA: 64] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Reconstituted collagen fibres have potential applications in repair of soft and hard tissues. Preliminary studies conducted in our laboratory suggest that discontinuous reconstituted type I fibres have strengths similar to those of fibres teased from tendons. The purpose of this paper is to report a method for continuous collagen fibre production and the properties of fibres produced. Ultimate tensile mechanical properties and biocompatibility of continuous type I collagen fibres were studied and compared with the properties of fibres produced manually (discontinuous fibres). In general, continuously made cyanamide cross-linked fibres show slightly inferior mechanical properties and faster biodegradation rates compared with manually made fibres because of minor differences in the fibreformation protocol introduced by design constraints. However, continuous and discontinuous fibres crosslinked with glutaraldehyde had comparable properties. These results demonstrate that production of 50 microns diameter continuous collagen fibre is possible.
Collapse
Affiliation(s)
- Y P Kato
- Department of Pathology, UMDNJ-Robert Wood Johnson Medical School, Piscataway 08854
| | | |
Collapse
|
12
|
Willey KP, Leidenberger F. Functionally Distinct Agonist and Receptor-binding Regions in Human Chorionic Gonadotropin. J Biol Chem 1989. [DOI: 10.1016/s0021-9258(19)47172-x] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
|
13
|
Magner JA. Thyroid-stimulating hormone: structure and function. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 1989; 261:27-103. [PMID: 2699971 DOI: 10.1007/978-1-4757-2058-7_4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Affiliation(s)
- J A Magner
- Michael Reese Hospital, University of Chicago, IL 60616
| |
Collapse
|
14
|
Bidart JM, Troalen F, Bohuon CJ, Hennen G, Bellet DH. Immunochemical mapping of a specific domain on human choriogonadotropin using anti-protein and anti-peptide monoclonal antibodies. J Biol Chem 1987. [DOI: 10.1016/s0021-9258(18)47752-6] [Citation(s) in RCA: 32] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
|
15
|
Hwang J, Menon KM. Characterization of the subunit structure of gonadotropin receptor in luteinized rat ovary. J Biol Chem 1984. [DOI: 10.1016/s0021-9258(17)43504-6] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
|
16
|
Ratanabanangkoon K, Keutmann HT, Kitzmann K, Ryan RJ. Properties of the phosphorylated beta subunit of human choriogonadotropin. J Biol Chem 1983. [DOI: 10.1016/s0021-9258(17)43894-4] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
|
17
|
Caamaño CA, Fernandez HN, Paladini AC. Specificity of covalently stabilized complexes of 125I-labeled human somatotropin and components of the lactogenic binding sites of rat liver. Biochem Biophys Res Commun 1983; 115:29-37. [PMID: 6311206 DOI: 10.1016/0006-291x(83)90964-6] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
125I-labeled human somatotropin specifically bound to the lactogenic sites of microsomal membranes from pregnant rat liver, originated a radioactive covalent complex of Mr 63,000 upon reaction with dimethyl suberimidate, disuccinimidyl suberate (DSS) and 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide. The amount of this species was closely parallel with the preexisting amount of the ligand-receptor complex. Photoactivation of a hormone derivative bound to the receptor also gave rise to the 63 K species. A ternary complex of receptor, hormone and Triton X-100 cross-linked with DSS yielded the 63 K species and a new one of 96 K. The data indicate that the 63 K complex involves the radioactive hormone and a constituent of the binding site. The 96 K species could comprise a second component of the receptor.
Collapse
|
18
|
Parsons TF, Pierce JG. Studies of the histidine residues of human and bovine glycoprotein hormones by nuclear magnetic resonance. INTERNATIONAL JOURNAL OF PEPTIDE AND PROTEIN RESEARCH 1983; 21:522-35. [PMID: 6411645 DOI: 10.1111/j.1399-3011.1983.tb02679.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Titration curves of the histidine residues in lutropin, thyrotropin, follitropin and chorionic gonadotropin have been assigned using imidazole C-2 proton nuclear magnetic resonance spectra and their estimated pK values determined. Spectra of reassociated hormone preparations, in which one or the other of their two subunits (alpha or beta) have had their accessible histidines exchanged with deuterium, permitted assignment of C-2 resonance to specific residues. Similar titration curves were found for residues which are conserved from one hormone to another. However, these conserved histidines do not have identical pK values, indicating that differences in the conformation or microenvironment around these residues occur in these hormones. Changes in some pK values also occur as a function of subunit association. The most dramatic change seen in all cases is the exposure to solvent of histidine alpha-83; in isolated alpha subunits this residue is unavailable for titration over a wide pH range. This change appears to be a general consequence of the association of the two subunits in any of these hormones. The data show that all histidines in the intact hormones are accessible to the environment, including those proposed to be in domains involved in subunit-subunit interaction.
Collapse
|
19
|
Weadock K, Olson RM, Silver FH. Evaluation of collagen crosslinking techniques. BIOMATERIALS, MEDICAL DEVICES, AND ARTIFICIAL ORGANS 1983; 11:293-318. [PMID: 6091801 DOI: 10.3109/10731198309118815] [Citation(s) in RCA: 203] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
The properties of collagen films crosslinked by physical and chemical techniques were compared to the properties of films crosslinked with glutaraldehyde (GTA). Physical techniques studied include exposure to short wave (254 nm) u.v. irradiation and severe dehydration. Chemical techniques studied include immersion of collagen films in aqueous solutions of cyanamide or GTA. Collagen films exposed to combinations of aqueous solutions of cyanamide and severe dehydration had moduli of elasticity, swelling ratios and resistance to bacterial collagenase similar to films crosslinked with GTA. Theoretical calculations based on amino acid composition indicate that approximately seven times as many amino acid residues are capable of forming crosslinks using cyanamide or severe dehydration procedures as compared to GTA crosslinking. In addition, using severe dehydration or cyanamide forms crosslinks involving both amino and carboxyl residues which may allow these procedures to act synergistically. Based on our studies this two-step procedure effectively crosslinks collagen-based biomaterials while the only by-product of this reaction is water-soluble urea. Preliminary biocompatibility studies suggest that this crosslinking procedure may allow for pronounced tissue ingrowth.
Collapse
|
20
|
Equine follicle-stimulating hormone. Purification, acid dissociation, and binding to equine testicular tissue. J Biol Chem 1981. [DOI: 10.1016/s0021-9258(19)68799-5] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
|
21
|
Abstract
Contact-site cross-linking agents comprise a heterogeneous grouping of cross-linkers which share the common property of being able to cross-link only very closely juxtaposed residues in macromolecular complexes. We have defined contact-site cross-linking arbitrarily as the covalent joining of residues such that they are constrained to a distance which is equivalent to or less than their closest possible steric approach prior to becoming linked (1). We recognize two classes of contact-site cross-linkers, bridge type and zero-length type. The former, such as formaldehyde, become incorporated during cross-linking as one-atom bridges. The latter, such as the carbodiimides, operate as condensing agents with the result that the cross-linked residues become interjoined directly. Contact-site cross-linkers have been used in several ways as specific probes of both the static and dynamic aspects of macromolecular structure. They can yield precise structural information about macromolecular contacts when actual sites of cross-linking are determined by peptide or nucleotide mapping techniques. In this way exact contacts between histones in the nucleosome, between protein and RNA in the ribosome, and between RNA polymerase and DNA have been determined. Contact-site cross-linkers have also been used to probe the perturbation of contacts following macromolecular conformational changes. Certain histone-histone 'cross-linkable' sites are rendered unreactive after induction of chromatin conformational changes thus serving to localize sites of perturbation.
Collapse
|
22
|
Myers M, Carter B. Adeno-associated virus replication. The effect of L-canavanine or a helper virus mutation on accumulation of viral capsids and progeny single-stranded DNA. J Biol Chem 1981. [DOI: 10.1016/s0021-9258(19)70007-6] [Citation(s) in RCA: 26] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
|
23
|
Pierce JG, Parsons TF. Glycoprotein hormones: similar molecules with different functions. UCLA FORUM IN MEDICAL SCIENCES 1980:99-117. [PMID: 400318 DOI: 10.1016/b978-0-12-643150-6.50014-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
|
24
|
Weare JA, Reichert LE. Studies with carbodiimide-cross-linked derivatives of bovine lutropin. I. The effects of specific group modifications on receptor site binding in testes. J Biol Chem 1979. [DOI: 10.1016/s0021-9258(18)50269-6] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
|