Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P01189 (beta-endorphin)
 21,003 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

During development of the calcitonin binding assay using rat brain particulate fraction, it was noticed that 125l-salmon calcitonin-l (125-SCT) was partly absorbed by the polypropylene tube surface in an irreversible manner. Absorption was partially prevented by cold SCT and complete prevention was achieved by bacitracin. Triton X-100, Brij 36T, and some Zwittergents in such concentration ranges which appeared not to disrupt the 125l-SCT binding ability of brain tissue. The brain fraction itself exhibited a similar preventive effect. The anti-absorbing effect of Brij 36T was also observed in an opiate receptor binding assay for beta-endorphin. These results led us to recommend that the binding assay for these peptides should be done only in the presence of an appropriate anti-absorbant.
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PMID:Absorption loss of peptides to the plastic tube in radioreceptor assay of calcitonin and beta-endorphin: protection by detergents. 628 68

Rat brain particulate fraction was found to contain binding sites for 125I-Salmon Calcitonin-I (125I-SCT). Maximum binding occurred in the physiological pH range of 7.25-7.5. The binding reaction proceeded in a temperature-dependent manner. Binding sites were broadly distributed among the various rat brain regions and considerable regional differences existed in the affinity and density as detected by Scatchard analysis. The highest affinity was recorded in the case of the hypothalamus and the lowest in the case of the cerebellum. The KD (nM) and Bmax (pmole/mg protein) estimated for the binding to four regions were as follows: hypothalamus: 1.4 and 0.19, midbrain, hippocampus plus striatum: 1.5 and 0.08, pons plus medulla oblongata: 3.0 and 0.15 and cerebellum: 8.3 and 0.20. Using a particulate fraction of rat brain void of cerebellum and cortices, a binding assay for calcitonins was developed. Binding of 125I-SCT was inhibited by unlabeled salmon, [Asu1,7]-eel and porcine calcitonins in a dose-dependent manner and the IC50s were 2.0, 8.0 and 30 nM, respectively. The IC50s were comparable to those estimated using a kidney particulate fraction. Human calcitonin, beta-endorphin and substance P were weak inhibitors of the binding. Other peptides, drugs and putative neurotransmitters tested (totally 23 substances) failed to inhibit the binding at concentrations of 1.0 microM. The physiological significance of brain binding sites for calcitonin, with the possibility that the brain may possess endogenous ligands for these sites are discussed.
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PMID:Specific binding of 125I-salmon calcitonin to rat brain: regional variation and calcitonin specificity. 725 44