TY - JOUR
T1 - Specific binding of 2-[125I]melatonin by partially purified membranes of rat thymus
AU - Lopez-Gonzalez, M. A.
AU - Martin-Cacao, A.
AU - Calvo, J. R.
AU - Reiter, R. J.
AU - Osuna, C.
AU - Guerrero, J. M.
N1 - Funding Information:
Supported by grants from Comision Interministerial de Ciencia y Tecnologia (PM91-0616) and Spain-USA Joint Committee. JMG was supported by a fellowship of the NATO Scientific Program.
PY - 1993/6
Y1 - 1993/6
N2 - Melatonin binding sites were characterized in partially rat thymus membranes. The specific binding of 2-[125I]iodomelatonin ([125I]MEL) to thymus membranes was dependent on time and temperature, stable, saturable, and reversible. Concentration-dependent binding of [125I]MEL to thymus membranes was saturable and resulted in a linear Scatchard plot, suggesting binding to a single class binding to sites. The Kd for this single site was 0.47 nM with a binding capacity of 1.01 pM. In competition studies, the specific binding of [125I]MEL to thymus membranes was inhibited by increasing concentrations of native melatonin. Scatchard analysis showed that, unlike in a saturation studies with [125I]MEL, data were compatible with the existence of two classes of binding sites: a high-affinity site with a Kd of 1.72 ± 0.25 nM and a binding capacity of 1.40 ± 0.18 pM, and a low-affinity site with a Kd of 1226 ± 325 Nm and a binding capacity of 460 ± 87 nM. Interestingly, Kd and BC values of the high-affinity binding site described by competition studies are similar to those obtained by saturation studies with [su125I]MEL. Binding of [125I]MEL to thymus membranes was specific as indicated by the fact no other precursor or derivative was as potent as melatonin in inhibiting the binding of [125I]MEL to membranes. Results strongly that melatonin is involved in regulation of thymus activity.
AB - Melatonin binding sites were characterized in partially rat thymus membranes. The specific binding of 2-[125I]iodomelatonin ([125I]MEL) to thymus membranes was dependent on time and temperature, stable, saturable, and reversible. Concentration-dependent binding of [125I]MEL to thymus membranes was saturable and resulted in a linear Scatchard plot, suggesting binding to a single class binding to sites. The Kd for this single site was 0.47 nM with a binding capacity of 1.01 pM. In competition studies, the specific binding of [125I]MEL to thymus membranes was inhibited by increasing concentrations of native melatonin. Scatchard analysis showed that, unlike in a saturation studies with [125I]MEL, data were compatible with the existence of two classes of binding sites: a high-affinity site with a Kd of 1.72 ± 0.25 nM and a binding capacity of 1.40 ± 0.18 pM, and a low-affinity site with a Kd of 1226 ± 325 Nm and a binding capacity of 460 ± 87 nM. Interestingly, Kd and BC values of the high-affinity binding site described by competition studies are similar to those obtained by saturation studies with [su125I]MEL. Binding of [125I]MEL to thymus membranes was specific as indicated by the fact no other precursor or derivative was as potent as melatonin in inhibiting the binding of [125I]MEL to membranes. Results strongly that melatonin is involved in regulation of thymus activity.
KW - Immune system
KW - Melatoni binding sites
KW - Melatonin
KW - Pineal
KW - Thymus
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U2 - 10.1016/0165-5728(93)90171-T
DO - 10.1016/0165-5728(93)90171-T
M3 - Article
C2 - 8331156
AN - SCOPUS:0027320109
VL - 45
SP - 121
EP - 126
JO - Advances in Neuroimmunology
JF - Advances in Neuroimmunology
SN - 0165-5728
IS - 1-2
ER -