HUCOLIN, A NEW CORTICOSTEROID-BINDING PROTEIN FROM HUMAN PLASMA WITH STRUCTURAL SIMILARITIES TO FICOLINS, TRANSFORMING GROWTH FACTOR-BETA-1-BINDING PROTEINS

In order to study the cortisol-binding factors in blood, human plasma was applied to a 11 beta-hydroxy-3-oxo-4-androstene-17 beta-carboxyaminoethylamine-(HACA) 1,4-butanediol diglycidyl ether-Sepharose column, Elution of the column with cortisol buffer produced two protein peaks, the minor peak yielded a protein complex of molecular weight similar to 200 kDa, subsequently termed hucolin. SDS-PAGE analysis under reducing and nonreducing conditions revealed hucolin was a disulphide-linked complex of 35-kDa and 75-kDa subunits, Twenty-five amino acid residues of the N-terminus of the 35-kDa subunit were determined and homology searches revealed an 88% sequence identity with the N-terminal region of beta-ficolin, a transforming growth factor-beta 1 (TGF-beta 1)-binding protein purified from porcine uterus.