alpha-2-HS-glycoprotein; alpha-2-Z-globulin; Ba-alpha-2-glycoprotein; fetuin-A (AHSG, FETUA, PRO2743)

Function: - negative acute phase reactant - promotes endocytosis - has opsonic properties - influences the mineral phase of bone - affinity for Ca⁺² & Ba⁺² - phosphorylation sites are present in the extracellular medium - alpha-2-HS glycoprotein derived from cleavage of connecting peptide from precursor - two chains A & B are held together by a single disulfide bond Structure: - O-glycosylated & N-glycosylated - O-glycosylated with core 1 glycan or possibly core 8 glycan - N-glycan at Asn-156: hex5hexNAc4; N-glycan - heterogeneity at Asn-176: hex5hexNAc4 (major) & hex6hexNAc5 (minor) - belongs to the fetuin family - contains 2 cystatin fetuin-A-type domains Compartment: - secreted - concentrated up to 300-fold in bone relative to other plasma proteins Expression: - synthesized in liver - secreted in plasma - selectively concentrated in bone matrix - also found in dentin in much higher quantities than other plasma proteins Polymorphism: - two common alleles, AHSG*1 & AHSG*2 - AHSG*1 has Thr-248/Thr-256; AHSG*2 has Met-248/Ser-256

General

acute phase protein alpha 2 globulin Ca+2 binding protein glycoprotein multisubunit protein opsonin phosphoprotein

Properties

SIZE: entity length = 367 aa MW = 39 kD COMPARTMENT: plasma MOTIF: signal sequence {1-18} Cystatin fetuin-A-type 1 {27-133} MOTIF: cysteine residue {C32} MODIFICATION: cysteine residue {C-INTERCHAIN} cysteine residue {C89} MODIFICATION: cysteine residue {C100} cysteine residue {C100} MODIFICATION: cysteine residue {C89} cysteine residue {C114} MODIFICATION: cysteine residue {C132} cysteine residue {C132} MODIFICATION: cysteine residue {C114} Ser phosphorylation site {S134} Ser phosphorylation site {S138} Cystatin fetuin-A-type 2 {144-255} MOTIF: cysteine residue {C146} MODIFICATION: cysteine residue {C149} cysteine residue {C149} MODIFICATION: cysteine residue {C146} N-glycosylation site {N156} N-glycosylation site {N176} cysteine residue {C208} MODIFICATION: cysteine residue {C219} cysteine residue {C219} MODIFICATION: cysteine residue {C208} cysteine residue {C230} MODIFICATION: cysteine residue {C247} cysteine residue {C247} MODIFICATION: cysteine residue {C230} Thr glycosylation site {T256} Thr glycosylation site {T270} Ser phosphorylation site {S325} Ser phosphorylation site {S328} Ser phosphorylation site {S330} Ser phosphorylation site {S334} Ser glycosylation site {S346}

Database Correlations

OMIM 138680 UniProt P02765 Pfam PF00031 Entrez Gene 197 KEGG correlations

References

OMIM :accession 138680