Purification and characterization of thyroid hormone-responsive rat hepatic proteins.
Bernal et al. identified two proteins in rat hepatic nuclear extract, t- and n-proteins, that were enriched by thyroidectomy or T3 treatment, respectively. We purified these proteins, raised monospecific antibodies, and characterized them by Western blotting. Anti-n and anti-t-protein antibodies did not recognize t- and n-proteins, respectively. The n-protein was present in nuclear and cytosolic fractions, was present at low levels in the microsomal fraction, and was absent in the mitochondrial fraction of rat liver. The t-protein was more abundant in mitochondrial and microsomal fractions than in the nuclear fraction. The t-protein had the same molecular mass and shared immunological properties with peroxisomal enoyl-coenzyme-A (CoA) hydratase-3-hydroxyacyl-CoA dehydrogenase bifunctional enzyme. The total cellular amount of n-protein increased 12 h after the administration of 1 microgram T3/100 g BW to thyroidectomized rats. Induction was obvious at 0.1 microgram T3/100 g BW after 24 h. Maximal induction was observed at 0.3 microgram T3/100 g BW. The n-protein was induced when thyroidectomized rat liver was perfused with 10(-7) M T3 for 6 h, excluding the possibility that the effect of T3 was mediated by an extrahepatic factor. The n-protein was detected in liver and brain, but not in kidney, heart, testis, or spleen. However, the amount of n-protein in brain was not thyroid hormone dependent. Hepatic n-protein does not correspond to any other T3-responsive protein in terms of its molecular mass and intracellular localization and may be a novel T3-responsive protein.
Miyamoto
T
T
Department of Gerontology, Endocrinology, and Metabolism, Shinshu University School of Medicine, Matsumoto-City, Japan.
Ichikawa
K
K
Hashizume
K
K
Nishii
Y
Y
Takeda
T
T
Kobayashi
M
M
Suzuki
S
S
Yamada
T
T
D015094:3-Hydroxyacyl CoA Dehydrogenases / Q000032:analysis / Q000737:chemistry; D000818:Animals; D015153:Blotting, Western; D002467:Cell Nucleus / Q000737:chemistry / Q000378:metabolism; D003600:Cytosol / Q000737:chemistry / Q000378:metabolism; D004746:Enoyl-CoA Hydratase / Q000032:analysis / Q000737:chemistry; D007535:Isomerases / Q000032:analysis / Q000737:chemistry; D008099:Liver / Q000737:chemistry / Q000187:drug effects / Q000378:metabolism*; D008297:Male; D008862:Microsomes, Liver / Q000737:chemistry / Q000378:metabolism; D008930:Mitochondria, Liver / Q000737:chemistry / Q000378:metabolism; D008970:Molecular Weight; D009097:Multienzyme Complexes / Q000032:analysis / Q000737:chemistry; D063994:Peroxisomal Bifunctional Enzyme; D014176:Protein Biosynthesis; D011506:Proteins / Q000737:chemistry / Q000302:isolation & purification; D051381:Rats; D011919:Rats, Inbred Strains; D013965:Thyroidectomy; D014284:Triiodothyronine / Q000494:pharmacology*
D009097:Multienzyme Complexes; D011506:Proteins; D014284:Triiodothyronine; D015094:3-Hydroxyacyl CoA Dehydrogenases; D004746:Enoyl-CoA Hydratase; D063994:Peroxisomal Bifunctional Enzyme; D007535:Isomerases