Characteristics of Soluble Gonadotropin Receptors for LH and hCG

Dufau, Maria L.; Ryan, Dene E.; Catt, K. J.

doi:10.1007/978-1-4684-2595-6_3

Cited by 16 publications

(16 citation statements)

References 12 publications

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“…Peak I eluted with the void volume and was presumed to be the hormonereceptor complex. This is consistent with the previously reported M, of 194,000 for the Triton X-100-soluble receptor (17,18). The slower migrating peak II is believed to be dissociated hormone.…”

supporting

confidence: 93%

“…that detergent-soluble l25I-hCG-receptor complex is precipitated in the presence of 12% polyethylene glycol while free hCG remains in solution (17,18). By If the biphasic curves shown in Fig.…”

mentioning

confidence: 96%

“…Table 1 indicates 0.2-0.3% crossreactivity of these antisera with hCGWe do not believe that solubilization of the hormone-receptor complex disrupts any crucial receptor protein interactions with the P subunit. Dufau et al (17,18) have shown that receptor solubilized with Triton X-100 retains both its specificity and affinity for hCG. Recently, it was reported that crosslinking hCG to the receptor before or after solubilization results in the same electrophoretic gel pattern, suggesting that the same receptor proteins are in contact with the hormone whether or not the receptor is solubilized with detergent (10,19).…”

mentioning

confidence: 99%

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Preferential masking by the receptor of immunoreactive sites on the alpha subunit of human choriogonadotropin.

Milius¹,

Midgley²,

Birken³

1983

Proc. Natl. Acad. Sci. U.S.A.

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'SI-Labeled human choriogonadotropin (5I-hCG) bound to rat ovarian receptor was solubilized in Triton X-100. By using increasing concentrations of nine different antisera specific for the individual subunits of human choriogonadotropin (hCG), free '25I-hCG or '25I-hCG-receptor complex was precipitated by double-antibody technique. The ability of any antiserum to bind to the hormone-specific ,B subunit was not affected by hCG binding to receptor, suggesting that this subunit is not directly involved with the receptor in the final state of the hormone-receptor complex. In contrast, every antiserum specific for the a subunit was dramatically inhibited in binding to the solubilized '25I-hCG-receptor complex. These results suggest that the a subunit directly interacts with the receptor, thereby masking immunoreactive sites normally available on the free hormone. Because a number of reports describe binding activity of high concentrations of immunopurified (8 subunits of hCG, we propose a two-step model for the binding of hCG to receptor and postulate separate and distinct roles for the subunits. We propose that the binding of hCG to the receptor involves a specific low-affinity initial interaction of the (3 subunit with the receptor that activates a second site for the high-affinity binding of a subunit and stabilization of the hormone-receptor complex.Lutropin (luteinizing hormone; LH), follitropin (follicle-stimulating hormone), and thyrotropin (thyrotropic hormone) are glycoprotein hormones secreted by the pituitary. Although the a subunits of these hormones are identical, each hormone binds to a different receptor. Specificity is somehow endowed by the , subunits, which are distinct for each hormone. Receptor binding and target-cell activation requires the association of both subunits because isolated subunits contain little or no activity (1). Human choriogonadotropin (hCG), a hormone secreted by the placenta during pregnancy, is a natural LH analog that shares this structure. Although the mechanisms of receptor binding and target-cell activation by these glycoprotein hormones have been extensively investigated, the exact roles of the subunits in these events are not well understood. A number of recent studies demonstrate that both subunits interact with the receptor (2-10), but they do not indicate whether either subunit has a greater role in high-affinity binding or in subsequent expression of biological activity.We have attempted to answer a portion of this question by using a number of polyclonal antisera specific for the subunits of hCG as probes to determine the relative availability of each subunit for binding to antibody after the hormone has bound to receptor. Unexpectedly, we find that all immunoreactive sites detectable on the (3 subunit of the free hormone are still available after the hormone has bound to receptor. In contrast, the number of antibody-binding sites on the a subunit are drastically decreased in the hCG-receptor complex. In light of these results, we present a two-step model f...

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supporting

confidence: 93%

mentioning

confidence: 96%

mentioning

confidence: 99%

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Preferential masking by the receptor of immunoreactive sites on the alpha subunit of human choriogonadotropin.

Milius¹,

Midgley²,

Birken³

1983

Proc. Natl. Acad. Sci. U.S.A.

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“…MArdh and co-workers (4,5) have reported that a similar pH optimum (pH 4.5) exists for whole gonococcal attachment to urothelial and vaginal epithelium. Similarly, the optimum pH for adenovirus attachment (6.0-8.0 [34]), adenovirus tail fiber attachment (pH 7.0 [35]), human chorionic gonadotropin, luteinizing hormone, and insulin binding (pH 7.4 [51], 7.6 [52], and 7.5 [56], respectively) are consistent with the environment in which they interact with their respective effector cells. Another explanation of the observed enhanced attachment at pH 4.5 is that pili may aggregate at or near pH 4.5.…”

Section: Adherence Of Isolated Gonococcal Pili To Human Cellsmentioning

confidence: 81%

Attachment role of gonococcal pili. Optimum conditions and quantitation of adherence of isolated pili to human cells in vitro.

Pearce¹,

Buchanan²

1978

J. Clin. Invest.

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A B S T R A C T Gonococcal pili facilitate attachment of virulent Neisseria gonorrhoeae to human cells. To characterize this attachment function, purified gonococcal pili isolated from four strains possessing antigenically distinct pili were radiolabeled with 125I and used to measure the attachment of pili to various human cells in vitro. Human buccal and cervical-vaginal mucosal epithelial cells, fallopian tube mucosa, and sperm bound pili in greater numbers per ,um2 of surface area (1-10) than fetal tonsil fibroblasts, HeLa M cells, erythrocytes, or polymorphonuclear leukocytes. This cell specificity of attachment suggests a greater density of membrane pili binding sites on cells similar or identical to cells from natural sites of infection. The pili binding sites were quantitated as 1 x 104 per cervical-vaginal squamous cell.Pili of all antigenic types attached equally to a given cell type, implying that the attachment moiety of each pilus was similar.Attachment of gonococcal pili to human cells occurred quickly with saturation of presumed receptor sites within 20-60 min. Attachment was temperature dependent (370 > 20°> 4°C), and pH dependent (3.5 < 4.5 > 5.5 > 7.5). Attachment was inhibited by antibody to pili (homologous pili Ab > heterologous Ab). The extent of possible protection against gonococcal infection due to inhibition of pili-mediated attachment might prove limited as a result of the considerable antigenic heterogeneity among pili and the observation that blockage of pili attachment is maximal only with antibody to pili of the infecting strain. INTRODUCTIONThe pili (fimbriae) of Neisseria gonorrhoeae presumably mediate the attachment of the gonococcus to human tissues. Previous evidence for an attachment role of pili has relied on the use of whole gonococci whose attachment to human cells was enhanced or occurred exclusively when that organism was piliated (1)(2)(3)(4)(5)(6)(7)(8). Swanson (1) has reported that the presence of pili afford gonococci enhanced attachment to human amnion cells in vitro. The adherence of gonococci to human buccal mucosal cells (2), ecto-and endocervical epithelium, and fallopian tube mucosa (3), as well as exfoliated vaginal (4) and urothelial cells (5) is also enhanced by piliation. James-Holmquist et al. (6, 7) further implicated an attachment role of pili by demonstrating that antibody to purified gonococcal pili blocked the enhanced attachment of piliated gonococci to human sperm. The human fallopian tube has been used in perfusion culture by Ward et al. (8) to provide scanning electron microscope evidence of pili anchoring gonococci to the epithelial surface. The agglutination of human erythrocytes by the gonococcus has been correlated with the presence of pili by several investigators (2, 9-12). Recently, purified pili alone have been shown to be capable of direct erythrocyte agglutination (12). This agglutination can be blocked by antiserum to these purified pili, and the blockage reflects the antigenic heterogeneity of gonococcal pili (12).For the gonococcus,...

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“…Another receptor of interest for DSD etiology is the receptor for LH and hCG (LHCGR), first characterized in 1974 [Dufau et al, 1974], for which the corresponding syndrome of LH resistance was clinically described as Leydig cell aplasia/hypoplasia in 1976 [Berthezene et al, 1976]. This discovery opened an explanation for solving a discussion in our team in Barcelona: an adult woman with a 46,XY karyotype and testes left intraabdominally at prepubertal surgery lacked any T response to hCG stimulation and had an otherwise normal steroidogenesis pattern.…”

Section: Peptide Hormone Mechanism Of Action: the Lh Receptor Storymentioning

confidence: 99%

Development of Laboratory Investigations in Disorders of Sex Development

Audí

Camats²,

Fernández‐Cancio³

et al. 2017

Sex Dev

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Scientific knowledge to understand the biological basis of sex development was prompted by the observation of variants different from the 2 most frequent body types, and this became one of the fields first studied by modern pediatric endocrinology. The clinical observation was supported by professionals working in different areas of laboratory sciences which led to the description of adrenal and gonadal steroidogenesis, the enzymes involved, and the different deficiencies. Steroid hormone measurements evolved from colorimetry to radioimmunoassay (RIA) and automated immunoassays, although gas and liquid chromatography coupled to mass spectrometry are now the gold standard techniques for steroid measurements. Peptide hormones and growth factors were purified, and their measurement evolved from RIA to automated immunoassays. Hormone action mechanisms were described, and their specific receptors were characterized and assayed in experimental materials and in patient tissues and cell cultures. The discovery of the genetic basis for variant sex developments began with the description of the sex chromosomes. Molecular technology allowed cloning of genes coding for the different proteins involved in sex determination and development. Experimental animal models aided in verifying the roles of proteins and also suggested new genes to be investigated. New candidate genes continue to be described based on experimental models and on next-generation sequencing of patient DNAs.

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Characteristics of Soluble Gonadotropin Receptors for LH and hCG

Cited by 16 publications

References 12 publications

Preferential masking by the receptor of immunoreactive sites on the alpha subunit of human choriogonadotropin.

Preferential masking by the receptor of immunoreactive sites on the alpha subunit of human choriogonadotropin.

Attachment role of gonococcal pili. Optimum conditions and quantitation of adherence of isolated pili to human cells in vitro.

Development of Laboratory Investigations in Disorders of Sex Development

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