Characterization of transthyretin in the Pacific bluefin tuna, Thunnus orientalis.
A cDNA encoding transthyretin was cloned from the Pacific bluefin tuna (Thunnus orientalis). This cDNA contains a complete open reading frame encoding 151 amino acid residues. The deduced amino acid sequence is 81% and 55% identical to the gilthead seabream and common carp forms, respectively, and 33-39% to mammalian, reptilian, and amphibian forms. A 1.0-kb transcript was found in the the liver and ovary; the liver is the main source of this protein. Analysis of triiodo-L-thyronine (T(3)) and L-thyroxine (T(4)) binding demonstrated that both T(3) and T(4) bind to bluefin transthyretin. The binding activity of T(3) for bluefin transthyretin is higher than that of T(4). These results indicate that bluefin transthyretin acts as a transporter of thyroid hormones (THs) in the plasma, and plays an important role in the function of THs in target cells.
Kawakami
Yutaka
Y
Department of Fisheries, Graduate School of Agriculture, Kinki University, Nara, Japan. yutakakjp@yahoo.co.jp
Seoka
Manabu
M
Miyashita
Shigeru
S
Kumai
Hidemi
H
Ohta
Hiromi
H
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D018076:DNA, Complementary / Q000032:analysis* / Q000737:chemistry; D005260:Female; D015870:Gene Expression; D008099:Liver / Q000378:metabolism*; D008297:Male; D008969:Molecular Sequence Data; D016366:Open Reading Frames; D010053:Ovary / Q000378:metabolism; D011228:Prealbumin / Q000737:chemistry / Q000235:genetics* / Q000302:isolation & purification*; D012333:RNA, Messenger / Q000096:biosynthesis; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000662:veterinary; D016415:Sequence Alignment; D012689:Sequence Homology, Nucleic Acid; D013963:Thyroid Hormones / Q000378:metabolism*; D013974:Thyroxine / Q000378:metabolism; D014284:Triiodothyronine / Q000378:metabolism; D014413:Tuna / Q000097:blood / Q000378:metabolism*
D018076:DNA, Complementary; D011228:Prealbumin; D012333:RNA, Messenger; D013963:Thyroid Hormones; D014284:Triiodothyronine; D013974:Thyroxine