Specific binding of 125I-salmon calcitonin to rat brain: Regional variation and calcitonin specificity.

Nakamuta, Hiromichi; Furukawa, Shoei; Koida, Masao; Yajima, Haruaki; Orlowski, Ronald C.; Schlueter, Robert J.

doi:10.1254/jjp.31.53

Cited by 68 publications

(17 citation statements)

References 27 publications

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“…Most tissues appear to possess a single class of CT receptors, although a second low-affinity site has been noted by some workers [8,11,15,47]. The reported maximum specific binding activities (Bmax) have ranged from 5 fmol/mg of protein for porcine lung membranes [13] to 190 fmol/mg of protein for rat hypothalamic homogenate [48]. Thus, the affinity of the placental CT receptor (mean Kd 80 + 21 pM, n = 4) is comparable with that of other physiological targets such as osteoclasts [5].…”

Section: Discussionmentioning

confidence: 99%

Human placental calcitonin receptors

Nicholson

D’Santos

Evans

et al. 1988

Biochemical Journal

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Receptors for the hypocalcaemic hormone, calcitonin (CT), have been identified in a membrane fraction prepared from term human placentae. Binding of 125I-labelled salmon CT (125I-sCT) to the membranes was time- and temperature-dependent, saturable (Bmax. 58 +/- 11 fmol/mg of protein), of high affinity (Kd 80 +/- 21 pM) and poorly reversible. Species-specific CTs and CT analogues competed for 125I-sCT binding with potencies proportional to their known biological potencies. Various unrelated peptide hormones did not compete, indicating that receptor binding was specific for CT. Photoaffinity labelling using a derivatized biologically active sCT analogue, [Arg11,18,3-nitrophenylazide-Lys14]sCT, identified a receptor component of Mr approximately 85,000, comparable with findings in osteoclasts and other target cells. The presence of CT receptors in the human placenta supports other evidence that CT may have a role in the regulation of placental function.

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Section: Discussionmentioning

confidence: 99%

Human placental calcitonin receptors

Nicholson

D’Santos

Evans

et al. 1988

Biochemical Journal

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“…It is known that when 1251-sCT at 1 nM was incubated in a polypropylene tube, most of the ligand would disappear from the incubation medium by irreversible absorption to the tube surface (12); and thus, all the binding assays of calcitonin reported so far have been carried out in the presence of an anti-absorbant such as bovine serum albumin, bacitracin or detergents (1)(2)(3)(4)12). None of them were employed in this experiment, however, because these surfactants invariably caused vigorous bubbling during incubation.…”

Section: Discussionmentioning

confidence: 99%

“…Recently, the calcitonin-specific binding sites were characterized in the rat brain (1)(2)(3)(4) and based on the regional and hormonal specificities of the sites, a functional relevancy to some in vivo effects of the hormone (e.g. anorectic) (5, 6) has been suggested.…”

Section: Abstract-itmentioning

confidence: 99%

A novel effect of salmon calcitonin on in vitro Ca-uptake by rat brain hypothalamus: The regional and hormonal specificities.

et al. 1982

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Abstract-itwas found that salmon calcitonin-I (sCT) inhibited in vitro 45Ca2+-uptake by rat brain hypothalamus blocks in a dose-dependent manner. The minimum effective concentration was estimated to be 10 nM or less. The effect appeared to be specific to the hypothalamus and was not observed with the pons plus medulla oblongata or the cerebral cortex. Two C-terminal fragments of the fish hormone, sCT (10-32) and sCT (22 32), and porcine calcitonin failed to inhibit the ion-uptake though tested in concentrations abolishing 1275I-sCT binding to these brain tissues, in dicating that the whole structure of sCT is essential for the inhibitory effect but not for the binding. Another finding to be noted was a possible de pendency of this effect on the integrity of the cell membrane structure. A crude synaptosomal fraction subsequently prepared from sCT-exposed hypothalamus blocks exhibited a decreased uptake of 45Ca2+, while a corresponding fraction from unexposed tissue did not respond to the hormone. These characteristics of this novel in vitro effect of sCT suggest its possible relevancy to the anorectic effect which also appears to be specific to the fish hormone.Recently, the calcitonin-specific binding sites were characterized in the rat brain (1-4) and based on the regional and hormonal specificities of the sites, a functional relevancy to some in vivo effects of the hormone (e.g. anorectic) (5, 6) has been suggested. Thus far, an elegant study by Miyahara and Oomura (7) seems to have succeeded in pinpointing the hypothalamic glucoreceptor as one of the sites.Peripherally, calcitonin regulates the blood Ca2+-level by changing the Ca-metabolism of bone and kidney tissues (8). An assumption was made that also in the central nervous system, the hormone would exert such behavioral effects by directly affecting the ion-metabolism, and using tissue blocks obtained from some brain regions, its effect on 45Ca2+-uptake was examined in vitro . We report herein that sCT specifically modified the ion-uptake of the rat hypothalamus, and

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“…A single binding site has been reported for the human breast cancer lines MCF7 and T47D [9, 101 and for such noncancerous tissues as calvaria [S, 111, cultured human lymphocytes [12, 131 and porcine lung [14]. Rat kidney cell membranes [3,8] and rat brain [15] appear to have two binding sites. Solubilization of calcitonin receptor from rat and pig kidney plasma membranes has been reported [16,171; both reports indicated that solubilization brought about a reduction in the value of the association constant.…”

Section: Purification and Characterization Of Calcitonin Receptors Inmentioning

confidence: 99%

Purification and characterization of calcitonin receptors in rat kidney membranes by covalent cross‐linking techniques

Bouizar

Fouchereau-Péron

Taboulet

et al. 1986

European Journal of Biochemistry

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We have characterized the binding parameters of renal receptors (Scatchard analysis revealed the presence of two binding sites: site I, K,, = 1.29 x lo9 M-', number of binding sites = 9.9 x 106/pg protein; site 11, Ka2 = 0.93 x 108M-', number of binding sites = 4.27 x 108/pg protein) and studied the effect of solubilization. The high-affinity sites are preserved during affinity chromatography and the process results in a 6080-fold purification of those sites. The lower-affinity sites are also preserved but the overall purification factor is about 40% lower than that obtained using molecular sieving. The purification of the renal calcitonin receptor by molecular sieving (Sephacryl S-200) is accompanied by total loss of the high-affinity site; however, the low-affinity site is enriched over 1642-fold. Binding parameters were obtained for the purified fractions. Synthetic salmon calcitonin was also bound to renal membranes using the bifunctional reagent disuccinimidyl suberate and photoaffinity cross-linking using hydroxysuccinimidyl azidobenzonate reagent. Cross-linked receptor eluted in the same volume as solubilized membranes specifically binding salmon calcitonin (S-200 chromatography).Sodium dodecyl sulfate polyacrylamide gel electrophoresis analysis of purified fractions showed several protein bands with apparent molecular masses ranging from 18000 Da to 100000 Da in the presence or absence of a reducing agent (2-mercaptoethanol). Autoradiography of polyacrylamide gels of cross-linked calcitonin receptor showed only three protein bands specifically binding salmon calcitonin. Their molecular masses were 70000 Da, 40000 Da and 33000 Da respectively. The 40000-Da molecule represents a major band (47% total binding species). This suggests that these three proteins are the principal components of the calcitonin receptor and that S-S bonds are not involved in the assembly of the receptor subunits.

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Specific binding of 125I-salmon calcitonin to rat brain: Regional variation and calcitonin specificity.

Cited by 68 publications

References 27 publications

Human placental calcitonin receptors

Human placental calcitonin receptors

A novel effect of salmon calcitonin on in vitro Ca-uptake by rat brain hypothalamus: The regional and hormonal specificities.

Purification and characterization of calcitonin receptors in rat kidney membranes by covalent cross‐linking techniques

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