title: Tissue-specific differences in the compartmentalization of rat nuclear triiodothyronine receptors.
abstract: In addition to the recognized rat liver nuclear T3 receptor extractable with hypertonic salt, recent studies have described nucleoplasmic receptors extractable with isotonic KCl and salt-resistant receptors localized to the nuclear matrix. A method was developed for the determination of intra-nuclear receptor distribution in small samples of nuclei dispersed within glass wool matrices. After in vitro labelling with 6 nmol/l [125I]T3, dispersed nuclei were sequentially extracted with 0.15 mol/l KCl (yielding nucleoplasmic receptors), 0.4 mol/l KCl. and 2 mol/l KCl (the latter two concentrations yielding hypertonic salt-extractable receptors). The salt-resistant receptors were retained within the glass wool columns. The intra-nuclear distribution of in vivo labelled receptors was very similar to that obtained by in vitro labelling. The equilibrium association constants for L-T3 binding among the receptor pools ranged from 0.6 X 10(9) to 1.0 X 10(9) l/mol. The distribution of total nuclear receptors within each nuclear compartment was (percentage of nucleoplasmic, hypertonic salt-extractable, and salt-resistant receptors): Cerebrum: 23.6, 52.2, 24.2; Liver: 25.2, 57.2, 17.5; Kidney: 45.9, 33.5, 20.6; Testis: 65.5, 14.7, 19.7; and Spleen: 66.7, 18.7, 14.6. The rank order of percentage of hypertonic salt-extractable receptors approximates the rank order of thyroid hormone-responsiveness by traditional criteria. The inverse is true for the percentage of nucleoplasmic receptors. The percentage of salt-resistant receptors was very similar in all of the tissues.
authors.affiliation: Department of Medicine, North Chicago VA Medical Center, Illinois.
authors.forename: C P
authors.initials: CP
authors.lastname: Barsano
authors.forename: Z
authors.initials: Z
authors.lastname: Iqbal
authors.forename: G L
authors.initials: GL
authors.lastname: Pullen
authors.forename: B E
authors.initials: BE
authors.lastname: Muñoz
authors.forename: S P
authors.initials: SP
authors.lastname: Singh
mesh_terms: D000818:Animals; D001923:Brain Chemistry; D002451:Cell Compartmentation; D002467:Cell Nucleus / Q000032:analysis*; D006982:Hypertonic Solutions; D007668:Kidney / Q000032:analysis; D008099:Liver / Q000032:analysis; D008297:Male; D009685:Nuclear Envelope / Q000032:analysis; D051381:Rats; D011919:Rats, Inbred Strains; D011988:Receptors, Thyroid Hormone / Q000302:isolation & purification* / Q000502:physiology; D013737:Testis / Q000032:analysis; D013963:Thyroid Hormones / Q000502:physiology
chemical_list: D006982:Hypertonic Solutions; D011988:Receptors, Thyroid Hormone; D013963:Thyroid Hormones