大鼠胸腺降黑素受体的鉴定及生物学特性  

Identification and Characterization of 2-[￣(125)I] Iodomelatonin Binding Sites in the Thymus of Rat

作　　者：刘志民[1] 赵瑛[1] 彭树勋[1] 

机构地区：[1]上海第二军医大学长征医院,香港大学生理系

出　　处：《标记免疫分析与临床》1995年第2期86-89,共4页Labeled Immunoassays and Clinical Medicine

摘　　要：应用放射配体结合法证实大鼠胸腺内存在降黑素特异结合部位，该结合位点可以满足特异结合部位的基本条件：１．低结合容量；２．高亲和力；３．可饱和性；４．可逆性；５．对降黑素高度特异性。此外，该特异结合位点具昼夜节律；亚细胞分布的研究表明以细胞核含量最高，线粒体次之，并具有年龄依赖性降低，以出生时最高。Melatonin binding sites in the thymus of rat were studied with 2-[125I]iodomelatonin ([125I]M)as a radioligand. Standard criteria for binding sites such as saturability, reversibility, specificity and high affinity were observed in the assay for the melatonin binding sites.Maximum binding capacity (Bmax)was 0.98±0.14 fmol/mg of protein and 0.96±0.14 fmol/mg of protein in mid-light(ML)and mid-dark(MD),respectively(P<0.05), which indicated that a circadian rhythm in [125I]M binding sites was present in the rat thymus. Equilibrium binding constant(Kd)was 51.4±10.6 and 52.8±9.0pmol/L in ML and MD, respectively(P<0.05).The subcellular distribution of binding sites in the rat thymus was in the following descending order :nuclear, mitochondrial, microsomal and cytosolic fraction.Meanwhile,an age-related decrease in [125I]M binding sites was also found .The findings demonstrate that [125I]M binding sites are present in the thymus.

关 键 词：降黑素 松果腺激素 放射配体测定 胸腺 大鼠 

分 类 号：Q456[生物学—生理学] Q576