Sexton P M, Houssami S, Hilton J M, O'Keeffe L M, Center R J, Gillespie M T, Darcy P, Findlay D M
St. Vincent's Institute of Medical Research Fitzroy, Victoria, Australia.
Mol Endocrinol. 1993 Jun;7(6):815-21. doi: 10.1210/mend.7.6.8395656.
Two rat calcitonin receptor isoforms have been identified by cDNA cloning from a hypothalamic library. The clones, C1a and C1b, specified proteins of 478 and 515 amino acids, respectively. The clones were identical, except that the C1b sequence encoded a 37-amino acid insert in the second extracellular domain, which conferred altered ligand recognition. Compared to the C1a receptor, expressed C1b receptors exhibited decreased affinity for porcine CT, relative to salmon CT, and negligible affinity for human CT. Clone C1b mRNA was predominately expressed in the brain, whereas mRNA for the C1a clone was present in both brain and peripheral tissues. Both receptors were able to couple functionally to adenylate cyclase. Thus, clone C1b represents a novel brain isoform of the CT receptor with different affinity for CT analogs resulting from an altered second extracellular domain.
通过从下丘脑文库中进行cDNA克隆，已鉴定出两种大鼠降钙素受体亚型。克隆体C1a和C1b分别编码478和515个氨基酸的蛋白质。除了C1b序列在第二个细胞外结构域编码一个37个氨基酸的插入片段外，这些克隆体是相同的，该插入片段导致配体识别发生改变。与C1a受体相比，表达的C1b受体对猪降钙素的亲和力相对于鲑鱼降钙素有所降低，而对人降钙素的亲和力可忽略不计。克隆体C1b mRNA主要在脑中表达，而C1a克隆体的mRNA则存在于脑和外周组织中。两种受体都能够在功能上与腺苷酸环化酶偶联。因此，克隆体C1b代表了一种新型的脑降钙素受体亚型，由于第二个细胞外结构域的改变，对降钙素类似物具有不同的亲和力。
