Promotes endocytosis, possesses opsonic properties and influences the mineral phase of bone. Shows affinity for calcium and barium ions. Alpha-2-HS glycoprotein derives from this precursor, when the connecting peptide is cleaved off. The two chains A and B are held together by a single disulfide bond. Synthesized in liver and selectively concentrated in bone matrix. Secreted in plasma. It is also found in dentin in much higher quantities than other plasma proteins. Phosphorylated by FAM20C in the extracellular medium. O- and N-glycosylated. O-glycosylated with core 1 or possibly core 8 glycans. N-glycan at Asn-156: Hex5HexNAc4; N-glycan heterogeneity at Asn-176: Hex5HexNAc4 (major) and Hex6HexNAc5 (minor). There are two common alleles, AHSG*1 and AHSG*2. AHSG*1 has Thr-248/Thr-256; AHSG*2 has Met-248/Ser-256. The disease may be caused by variants affecting the gene represented in this entry. Belongs to the fetuin family.