Cloning and characterization of type III iodothyronine deiodinase from the fish Oreochromis niloticus
| Autor: | J P, Sanders, S, Van der Geyten, E, Kaptein, V M, Darras, E R, Kühn, J L, Leonard, T J, Visser |
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| Rok vydání: | 1999 |
| Předmět: |
Models
Molecular DNA Complementary Rana catesbeiana Base Sequence Sequence Homology Amino Acid Molecular Sequence Data Iodide Peroxidase Recombinant Proteins Kinetics Xenopus laevis Organ Specificity Animals Humans Nucleic Acid Conformation Amino Acid Sequence Cloning Molecular 3' Untranslated Regions Chickens Sequence Alignment Tilapia |
| Zdroj: | Endocrinology. 140(8) |
| ISSN: | 0013-7227 |
| Popis: | Type III iodothyronine deiodinase (D3) catalyzes the inner ring deiodination (IRD) of T4 and T3 to the inactive metabolites rT3 and 3,3'-diiodothyronine (3,3'-T2), respectively. Here we describe the cloning and characterization of complementary DNA (cDNA) coding for D3 in fish (Oreochromis niloticus, tilapia). This cDNA contains 1478 nucleotides and codes for a protein of 267 amino acids, including a putative selenocysteine (Sec) residue, encoded by a TGA triplet, at position 131. The deduced amino acid sequence shows 57-67% identity with frog, chicken, and mammalian D3, 33-39% identity with frog, fish (Fundulus heteroclitus) and mammalian D2, and 30-35% identity with fish (tilapia), chicken, and mammalian D1. The 3' UTR contains a putative Sec insertion sequence (SECIS) element. Recombinant tilapia D3 (tD3) expressed in COS-1 cells and native tD3 in tilapia brain microsomes show identical catalytic activities, with a strong preference for IRD of T3 (Km approximately 20 nM). IRD of [3,5-125I]T3 by native and recombinant tD3 are equally sensitive to inhibition by substrate analogs (T3T4rT3) and inhibitors (gold thioglucoseiodoacetatepropylthiouracil). Northern analysis using a tD3 riboprobe shows high expression of a 1.6-kb messenger RNA in gill and brain, although D3 activity is much higher in brain than in gill. The characterization of tD3 cDNA provides new information about the structure-activity relationship of iodothyronine deiodinases and an important tool to study the regulation of thyroid hormone bioactivity in fish. |
| Databáze: | OpenAIRE |
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