The Contribution of Subunits of Thyroid Stimulating Hormone to the Binding and Biological Activity of Thyrotropin

Wolff, Joachim R.; Winand, René; Kohn, Leonard D.

doi:10.1073/pnas.71.9.3460

Cited by 49 publications

(9 citation statements)

References 22 publications

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“…respectively) translocates within the membrane domain to interact with adenylate cyclase and to significantly alter ion transport. Such a mechanism is in accord with our previous study (24) suggesting that the TSH (3subunit contains determinants for TSH-receptor binding, whereas the a-subunit does not. It is further in accord with data (24) that indicate that a specific conformation of the TSH molecule is required for adenylate cyclase stimulation and that this conformation, despite a common and interchangeable a subunit, is distinct from the conformation of luteinizing hormone after it interacts with the TSH receptor.…”

Section: Resultssupporting

confidence: 80%

Thyrotropin-ganglioside interactions and their relationship to the structure and function of thyrotropin receptors.

Mullin¹,

Fishman²,

Lee³

et al. 1976

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

196

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Gangliosides inhibit 1251-labeled thyrotropin binding to the thyrotropin receptors on bovine thyroid plasma membranes, on guinea pig retro-orbital tissue plasma membranes, and on human adipocyte membranes. This inhibition by gangliosides is critically altered by the number and location of the sialic acid residues within the ganglioside structure, the efficacy of inhibition having the following order: GD1b > GTI > GM1 > GM2 = GM3 > GD1a. The inhibition results from the interaction of thyrotropin and gangliosides, rather than the interaction of membrane and gangliosides. Fluorescence studies show that the inhibition is associated with a distinct conformational change of the thyrotropin molecule and that the progression from a "noninhibitory conformation" to an "inhibitory conformation" parallels exactly the order of effectiveness in inhibiting 125I-Yabeled thyrotropin binding. The ganglioside inhibition of 1251-labeled thyrotropin binding appears to be hormonally specific in that it is not affected by a umin, glucagon, insulin, prolactin, follicle-stimulating hormone, growth hormone, or corticotropin. The possibility that a ganglioside or ganglioside-like structure is a component of the thyrotropin receptor is suggested by the finding that gangliosides more complex than N-acetylneuraminylgalactosylglucosylceramide are present in bovine thyroid membranes in much higher quantities than have been previously found in extraneural tissue. The finding that the B component of cholera toxin, which also interacts with gangliosides, has a peptide sequence in common with the f, subunit of thyrotropin, suggests that thyrotropin and cholera toxin may be analogous in their mode of action on the membrane.In previous studies that detailed the solubilization of the thyrotropin (TSH) receptor from bovine thyroid plasma membranes, tryptic digestion was shown to yield a receptor fragment that exhibited specific TSH binding and had properties similar to those exhibited by the TSH receptor prior to solubilization (1, 2). This receptor fragment was purified by chromatography over TSH-Sepharose preparations (1, 2); it was shown to have a molecular weight of 25,000-30,000 by gel electrophoresis in the presence of sodium dodecyl sulfate (2), and to contain 30% carbohydrate and 10% sialic acid by weight (1). The sialic acid was vital to receptor function since neuraminidase digestion eliminated the ability of both the purified receptor fragment and the crude solubilized receptor preparation to specifically bind TSH (1).Recent studies have indicated that gangliosides, glycosphingolipids that contain sialic acid, specifically interact with cholera toxin and that variations in the oligosaccharide structure of the gangliosides influence this interaction (3-5). The present report demonstrates that TSH also interacts with gangliosides and that the location and number of the sialic acid residues on the ganglioside molecule is critical to this interaction. The report further shows that there is a sequence homology in the B component of chole...

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Section: Resultssupporting

confidence: 80%

Thyrotropin-ganglioside interactions and their relationship to the structure and function of thyrotropin receptors.

Mullin¹,

Fishman²,

Lee³

et al. 1976

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

196

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“…The in vitro affinity of TSH for various gangliosides (1) is close to that of interferon (5-7), whereas that reported for cholera toxin is not (3)(4)(5)(6)(7)(8)(9)(10)(11)(12). The simple inhibitory effect of interferon on TSH binding and the complex effect on cholera toxin binding (Fig.…”

Section: Discussionmentioning

confidence: 95%

“…The B protein of cholera toxin and the # subunit of TSH appear to carry the primary determinants for their interaction with the ganglioside or ganglioside-like structures on the cell membrane (8)(9)(10)(11)(12). Recent reports have defined a common region of primary sequence on these subunits and have suggested that this sequence may be one of the structural determinants important in the interaction of TSH and cholera toxin with specific receptor structures on the surface of the cell (1,3).…”

mentioning

confidence: 99%

Use of thyrotropin and cholera toxin to probe the mechanism by which interferon initiates its antiviral activity.

Kohn¹,

Friedman²,

Holmes³

et al. 1976

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

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Thyrotropin (10 gM) inhibited the antiviral activity of interferon. When added after interferon, thyrotropin (TSH) had no effect on antiviral activity. There was also no inhibition of interferon action in cells washed with medium between incubations with TSH and interferon.125I-Labeled TSH and 125I-labeled cholera toxin could bind to preparations of mouse L-cell plasma membranes. The binding was specific in that it was prevented by unlabeled thyrotropin or cholera toxin, but not by insulin, glucagon, prolactin, growth hormone, human chorionic gonadotropin, or luteinizing hormone.Mouse interferon inhibited 125I-labeled TSH binding to L-cell plasma membranes. The effect of mouse interferon on 125I-labeled cholera toxin binding was more complex, inhibition occurring only after an initial enhancement at low interferon concentrations. A 10-fold higher concentration of interferon was required to inhibit 25I-labeled cholera toxin binding as compared to 25I-labeled TSH binding. Mouse interferon was also able to displace bound 125I-labeled TSH, but not bound 125I-labeled cholera toxin. The interferon interaction with cell membranes was temperature-sensitive.Human interferon could induce changes in binding of 125I-labeled TSH and 125I-labeled cholera toxin to mouse L-cell plasma membranes similar to those induced by mouse interferon. Mouse interferon induced similar changes in plasma membranes of human KB-3 cells, which are insensitive to both human and mouse interferons. In view of these results, the species specificity of interferons does not appear to reside solely at the point of the initial interaction with their binding sites. The mechanism by which thyrotropin (TSH) and cholera toxin transmit their message to the cell is believed to require a multistep sequence of events whose main contributors are, in turn, a specific ganglioside or ganglioside-like receptor structure, a significant alteration in the state of the membrane, an effector-responsive adenylate cyclase, and cell metabolism susceptible to regulation by the increased production of adenosine 3':5'-cyclic monophosphate (1)(2)(3)(4).Interferon initiates an antiviral state by interacting with receptors which, like those for cholera toxin or TSH, may be gangliosides or ganglioside-like structures containing an oligosaccharide moiety as a critical feature of their structure (5-7). The evidence for a ganglioside or a ganglioside-like structure of the interferon binding site is: Phaseolus vulgaris phytohemagglutinin blocks interferon action (5); Sepharose-bound interferon loses its antiviral activity after preincubation with gangliosides (6); soluble interferon binds to Sepharose-bound gangliosides (6); interferon binding to gangliosides is inhibited by phytohemagglutinin (6); and sialyl-lactose reverses the ability of gangliosides to inhibit the action of interferon (7).The B protein of cholera toxin and the # subunit of TSH appear to carry the primary determinants for their interaction with the ganglioside or ganglioside-like structures on the cell memb...

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“…To ensure minimal contamination by TSH they were individually rechromatographed on Sephadex G100. Bovine luteinizing hormone (LH) and the subunits of LH were also prepared as described (14)(15)(16); the LH subunits were also individually rechromatographed on Sephadex G100 to minimize native hormone contamination.…”

Section: Hormone and Subunit Preparationsmentioning

confidence: 99%

Exophthalmogenic Activity of the β Subunit of Thyrotropin

Kohn¹,

Winand²

1975

Endocrinology

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The Contribution of Subunits of Thyroid Stimulating Hormone to the Binding and Biological Activity of Thyrotropin

Abstract: The binding of bovine TSH

Cited by 49 publications

References 22 publications

Thyrotropin-ganglioside interactions and their relationship to the structure and function of thyrotropin receptors.

Thyrotropin-ganglioside interactions and their relationship to the structure and function of thyrotropin receptors.

Use of thyrotropin and cholera toxin to probe the mechanism by which interferon initiates its antiviral activity.

Exophthalmogenic Activity of the β Subunit of Thyrotropin

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