PROTEIN HC A low molecular weight plasma protein

Protein HC or alpha-1-microglobulin is a human glycoproteinof low molecular weight (25-30,000) present in plasma, urine and cerebrospinal fluid. It also occurs in association with the surface of various human cell types.
The protein, containing only one polypeptide chain, is heterogeneous in charge, even when desialylated, has a marked tendency to form complexes with other plasma proteins, e.g., IgA and albumin, and is strongly associated with an unidentified chromophore material(s) that gives the purified protein a light brown color. Its amino-terminal amino acid sequence is:
Gly-Pro-Val-Pro-Arg-Pro-Pro-Asp-Asn-Ile-Gln-Val-Gln-Glu-Asn-Phe-Phe-Ile-Ser-Arg-Ile-Tyr-Gly-Arg-Trp-Tyr-Asn-Leu-Ile-Ala

The kidney is probablythe main site of its catabolism and the liver producesappreciable amounts of the protein.

The mean adult normal plasma concentration has been estimated to be 32-98 mg/L. The protein is not an acute phase reactant. The plasma level of the protein is higher in males than in females and increases during pregnancy. Young fetuses have serum levels exceeding those in adults, but levels in cord blood are lower than in maternal plasma.