title: Application of a mathematical model for two component receptor binding to two high affinity oestrogen binding sites in nuclei from DMBA rat mammary tumours.
abstract: Saturation binding of [3H]oestradiol has been determined using exchange conditions, on nuclei from DMBA tumours from rats treated prior to sacrifice with oestradiol and tamoxifen alone or in combination. Application of a model to the binding data enabled the amounts (C2) and apparent dissociation constants (Kdapp) of a second lower affinity binding component to be determined as well as the amount of a higher affinity site (C1) and its dissociation constant (Kd1). Kdapp did not change significantly with any pretreatment but 2 h after oestradiol (5 micrograms) and after tamoxifen alone there was a significant decrease in Kd compared with control. It is suggested that the difference in Kd of the higher affinity binding sites in control and 2 h oestradiol treated animals may be due to the loss of an essential co-factor, possibly cytosolic, when nuclei are isolated in the absence of ligand.
mesh_terms: D015127:9,10-Dimethyl-1,2-benzanthracene; D000818:Animals; D001665:Binding Sites; D002467:Cell Nucleus / Q000378:metabolism; D004958:Estradiol / Q000378:metabolism; D008325:Mammary Neoplasms, Experimental / Q000378:metabolism*; D008433:Mathematics; D008962:Models, Theoretical; D051381:Rats; D011960:Receptors, Estrogen / Q000378:metabolism*; D013629:Tamoxifen / Q000378:metabolism
chemical_list: D011960:Receptors, Estrogen; D013629:Tamoxifen; D004958:Estradiol; D015127:9,10-Dimethyl-1,2-benzanthracene