Regulation of thyroid hormone binding to its cytosolic binding protein by L-alpha-alanine.
The human cytosolic thyroid hormone binding protein (p58) was recently shown to be a monomer of pyruvate kinase, subtype PKM2, and have intrinsic pyruvate kinase activity. The present study evaluated the effect of L-alpha-alanine on the binding of 3,3',5-triiodo-L-thyronine (T3) and enzymatic activity of p58. Analysis of the competitive binding data indicated that alanine, at the physiological concentration, is a non-competitive inhibitor of T3 binding to p58. Furthermore, alanine was found to be a "mixed" inhibitor of the substrate phosphoenol pyruvate. However, binding of alanine to p58 did not block the association of p58 to form the tetrameric pyruvate kinase.
Ashizawa
K
K
Laboratory of Molecular Biology, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892.
Kato
H
H
McPhie
P
P
Cheng
S
S
D000409:Alanine / Q000494:pharmacology*; D002352:Carrier Proteins / Q000378:metabolism*; D002460:Cell Line; D003600:Cytosol / Q000378:metabolism; D006801:Humans; D007700:Kinetics; D008565:Membrane Proteins / Q000378:metabolism*; D008962:Models, Theoretical; D013963:Thyroid Hormones; D014284:Triiodothyronine / Q000378:metabolism*; D000097810:Thyroid Hormone-Binding Proteins
D000409:Alanine; D002352:Carrier Proteins; D008565:Membrane Proteins; D013963:Thyroid Hormones; D014284:Triiodothyronine; D000097810:Thyroid Hormone-Binding Proteins