title: Corticosteroid binding globulin, testosterone-estradiol binding globulin, and androgen binding protein belong to protein families distinct from steroid receptors.
abstract: The cDNA nucleotide sequences and the deduced amino acid sequences of human corticosteroid binding globulin (hCBG), human testosterone-estradiol binding globulin (hTeBG), and rat androgen binding protein (rABP) were determined. Studies of the steroid binding sites suggest they are toward the carboxy-terminus in hTeBG and rABP and more central in hCBG. hCBG has remarkable sequence homology with members of a superfamily whose functions have diverged; these include thyroxine-binding protein, serine protease inhibitors, egg white proteins, and angiotensinogen. hTeBG and rABP have a 68% amino acid sequence identity. Hybridization studies suggest that hTeBG is probably even more closely related, if not identical, to hABP. The carboxy-terminal sequences of hTeBG and rABP are also similar to that of protein S, a vitamin-K-dependent clotting factor. There were no nucleotide or amino acid sequence homologies between hCBG, hTeBG, or rABP and other steroid binding proteins such as steroid receptors, albumin, alpha-fetoprotein, and vitamin D binding protein. We conclude that the "extracellular steroid binding proteins" and steroid receptors do not appear to have descended from a common ancestor.
authors.affiliation: Population Council, New York, NY 10021.
authors.forename: C W
authors.initials: CW
authors.lastname: Bardin
authors.forename: G L
authors.initials: GL
authors.lastname: Gunsalus
authors.forename: N A
authors.initials: NA
authors.lastname: Musto
authors.forename: C Y
authors.initials: CY
authors.lastname: Cheng
authors.forename: J
authors.initials: J
authors.lastname: Reventos
authors.forename: C
authors.initials: C
authors.lastname: Smith
authors.forename: D A
authors.initials: DA
authors.lastname: Underhill
authors.forename: G
authors.initials: G
authors.lastname: Hammond
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D003001:Cloning, Molecular; D004247:DNA / Q000235:genetics; D005796:Genes; D006801:Humans; D008969:Molecular Sequence Data; D011987:Receptors, Steroid / Q000235:genetics*; D012689:Sequence Homology, Nucleic Acid; D012738:Sex Hormone-Binding Globulin / Q000235:genetics*; D014156:Transcortin / Q000235:genetics*
chemical_list: D011987:Receptors, Steroid; D012738:Sex Hormone-Binding Globulin; D004247:DNA; D014156:Transcortin