Fetuin: The bovine homologue of human α2HS glycoprotein

Abstract

The fetal protein fetuin has previously been considered to be confined to species of the order Artiodactyla (cattle, sheep, etc.) in spite of demonstrable biological in vitro effects in tissues of other species [(1983) Comp. Biochem. Physiol. 76A, 241–245]. We have determined the partial amino acid sequence of bovine fetuin and compared it with the published sequence of human α₂HS glycoprotein. The N‐terminal 105 residues and a segment aligned with residues 170–225 of α₂HS glycoprotein revealed 109 of 161 residues to be identical between the two proteins (68% homology). Mouse polyclonal antibodies to fetuin, and trypsin digest fragments of this protein have been prepared and used for a comparison of native and digested proteins. Polyclonal antibodies to native protein showed little if any cross reactivity. However, antibodies to trypsin digest fragments of fetuin showed obvious cross reactivity with α₂HS.