Presence of three different binding sites for retinoids, bilirubin and estrogen or arachidonic acid on rat alpha-fetoprotein.
Rat alpha-fetoprotein (AFP) contains one binding site for estradiol with an association constant, Ka = 1 X 10(8) M-1. This site overlaps with a high affinity arachidonic acid binding site (Ka = 1 X 10(7) M-1) and with a tryptophan methyl ester binding site, AFP also possesses a second site able to bind retinoids with a Ka = 1 X 10(6) M-1, and a third site for the binding of bilirubin (Ka = 1 X 10(6) M-1). These two sites presented no interaction and do not overlap with the estrogen or fatty acid binding site. It is suggested that these three binding sites reflect the three-domain structure of the rat AFP molecule deduced from the studies on the nucleotide sequence of AFPmRNA and AFPcDNA segments.
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Aussel
D000818:Animals; D016718:Arachidonic Acid; D001095:Arachidonic Acids / Q000378:metabolism*; D001663:Bilirubin / Q000378:metabolism*; D001665:Binding Sites; D001667:Binding, Competitive; D003956:Dialysis; D004967:Estrogens / Q000378:metabolism*; D005260:Female; D008024:Ligands; D011247:Pregnancy; D051381:Rats; D011919:Rats, Inbred Strains; D012176:Retinoids / Q000378:metabolism*; D014316:Tritium; D000509:alpha-Fetoproteins / Q000032:analysis* / Q000378:metabolism
D001095:Arachidonic Acids; D004967:Estrogens; D008024:Ligands; D012176:Retinoids; D000509:alpha-Fetoproteins; D014316:Tritium; D016718:Arachidonic Acid; D001663:Bilirubin