Saturable triiodothyronine-binding sites in the pituitary nuclei of salmonid teleost fish

Journal Article · Mon Jan 01 00:00:00 EST 1990 · General and Comparative Endocrinology; (USA)

DOI:https://doi.org/10.1016/0016-6480(90)90202-W· OSTI ID:7168392

Bres, O; Eales, J G ^[1]

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1. Univ. of Manitoba, Winnipeg (Canada)

High-affinity, limited-capacity, 3,5,3'-triiodo-L-thyronine (T3)-binding sites were established by in vitro saturation analysis in cell nuclei of the pituitary gland of arctic charr. The sites were extracted from the purified nuclei using 0.4 M NaCl and incubated with ({sup 125}I)T3 in the presence of 0.2 M NaCl. T3 saturable binding attained equilibrium after 18-24 hr of incubation at 4 degrees. The association constant ranged from 6.7 to 20.1 liters.mol-1 x 10(9), indicating a T3 affinity greater than that for T3-binding sites in rainbow trout liver. The maximal binding capacity ranged from 0.93 to 2.05 10(-13) mol.mg DNA-1, representing a mean site abundance corresponding to 60% of that for nuclei from trout liver. Thyroxine (T4) completely displaced ({sup 125}I)T3 in the pituitary nuclei of arctic charr and T3 completely displaced ({sup 125}I)T4 in the pituitary nuclei of rainbow trout, suggesting that in salmonids both T4 and T3 bind to the same single class of sites. However, the site affinity for T4 was approximately 20-50x less than that for T3. The possible roles of these sites in pituitary function as well as their relationship to other nuclear T3-binding sites in salmonid fish are discussed.

• OSTI ID: 7168392
• Journal Information: General and Comparative Endocrinology; (USA), Vol. 77:1; ISSN 0016-6480
• Country of Publication: United States
• Language: English

Related Subjects

59 BASIC BIOLOGICAL SCIENCES
PITUITARY GLAND
BIOLOGICAL FUNCTIONS
TRIIODOTHYRONINE
RECEPTORS
AFFINITY
BIOCHEMICAL REACTION KINETICS
CELL NUCLEI
DNA
IODINE 125
THYROXINE
TRACER TECHNIQUES
TROUT
AMINO ACIDS
ANIMALS
AQUATIC ORGANISMS
BETA DECAY RADIOISOTOPES
BODY
CARBOXYLIC ACIDS
CELL CONSTITUENTS
DAYS LIVING RADIOISOTOPES
ELECTRON CAPTURE RADIOISOTOPES
ENDOCRINE GLANDS
FISHES
FUNCTIONS
GLANDS
HORMONES
INTERMEDIATE MASS NUCLEI
IODINE ISOTOPES
ISOTOPE APPLICATIONS
ISOTOPES
KINETICS
MEMBRANE PROTEINS
NUCLEI
NUCLEIC ACIDS
ODD-EVEN NUCLEI
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC HALOGEN COMPOUNDS
ORGANIC IODINE COMPOUNDS
ORGANS
PEPTIDE HORMONES
PROTEINS
RADIOISOTOPES
REACTION KINETICS
THYROID HORMONES
VERTEBRATES
550201* - Biochemistry- Tracer Techniques