Cloning of a cDNA for the Type II Iodothyronine Deiodinase

doi:10.1074/jbc.270.45.26786

Cloning of a cDNA for the Type II Iodothyronine Deiodinase (*)

From the Departments of Physiology and Medicine, Dartmouth Medical School, Lebanon, New Hampshire 03756

^§ To whom correspondence should be addressed:
Dept. of Physiology, Dartmouth Medical School, Borwell Bldg., 1 Medical Center Dr., Lebanon, NH 03756
. Tel.: 603-650-7735; Fax: 603-650-6130.

Abstract

Three types of iodothyronine deiodinase have been identified in vertebrate tissues. cDNAs for the types I and III have been cloned and shown to contain an in-frame TGA that codes for selenocysteine at the active site of the enzyme. We now report the cloning of a cDNA for a type II deiodinase using a reverse transcription/polymerase chain reaction strategy and RNA obtained from Rana catesbeiana tissues. This cDNA (RC5′DII) manifests limited but significant homology with other deiodinase cDNAs and contains a conserved in-frame TGA codon. Injection of capped in vitro synthesized transcripts of the cDNA into Xenopuslaevis oocytes results in the induction of deiodinase activity with characteristics typical of a type II deiodinase. The levels of RC5′DII transcripts in R. catesbeiana tadpole tail and liver mRNA at stages XII and XXIII correspond well with that of type II deiodinase activity but not that of the type III activity in these tissues. These findings indicate that the amphibian type II 5′-deiodinase is a structurally unique member of the family of selenocysteine-containing deiodinases.

Footnotes

↵* This work was supported by the following grants from the National Institutes of Health: HD 09020 and HD 27706 (to V. A. G.), DK 07508 (to K. B. B.), and DK 42271 (to D. L. S.). The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore by hereby marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.

The nucleotide sequence(s) reported in this paper has been submitted to the GenBank™/EMBL Data Bank with accession number(s) L42815[GenBank].
↵¹ The abbreviations used are:

T

thyroxine

T

3,5,3′-triiodothyronine

rT

3,3′,5′-triiodothyronine

5DI

type I deiodinase

5DII

type II deiodinase

5DIII

type III deiodinase

5′D

5′-deiodination

5D

5-deiodination

RC5D

cDNA for the R. catesbeiana type III deiodinase

bp

base pair(s)

kb

kilobase(s)

PTU

6n-propyl 2-thiouracil

AThG

aurothioglucose

RT/PCR

reverse transcription/polymerase chain reaction

RACE

rapid amplification of cDNA ends

UAP

universal amplification primer.
↵² D. L. St. Germain, unpublished observations.
↵³ W. Croteau and D. L. St. Germain, unpublished data.
- Received August 3, 1995.
- Revision received August 23, 1995.