alpha(1)-Microglobulin: a yellow-brown lipocalin

Biochim Biophys Acta. 2000 Oct 18;1482(1-2):172-84. doi: 10.1016/s0167-4838(00)00157-6.


alpha(1)-Microglobulin, also called protein HC, is a lipocalin with immunosuppressive properties. The protein has been found in a number of vertebrate species including frogs and fish. This review summarizes the present knowledge of its structure, biosynthesis, tissue distribution and immunoregulatory properties. alpha(1)-Microglobulin has a yellow-brown color and is size and charge heterogeneous. This is caused by an array of small chromophore prosthetic groups, attached to amino acid residues at the entrance of the lipocalin pocket. A gene in the lipocalin cluster encodes alpha(1)-microglobulin together with a Kunitz-type proteinase inhibitor, bikunin. The gene is translated into the alpha(1)-microglobulin-bikunin precursor, which is subsequently cleaved and the two proteins secreted to the blood separately. alpha(1)-Microglobulin is found in blood and in connective tissue in most organs. It is most abundant at interfaces between the cells of the body and the environment, such as in lungs, intestine, kidneys and placenta. alpha(1)-Microglobulin inhibits immunological functions of white blood cells in vitro, and its distribution is consistent with an anti-inflammatory and protective role in vivo.

Publication types

  • Review

MeSH terms

  • Alpha-Globulins / chemistry*
  • Alpha-Globulins / genetics
  • Alpha-Globulins / immunology
  • Alpha-Globulins / metabolism*
  • Animals
  • Humans
  • Immunity
  • Membrane Glycoproteins / biosynthesis
  • Models, Molecular
  • Protein Conformation
  • Protein Processing, Post-Translational
  • Tissue Distribution
  • Trypsin Inhibitor, Kunitz Soybean*


  • Alpha-Globulins
  • Membrane Glycoproteins
  • SPINT2 protein, human
  • alpha-1-microglobulin
  • Trypsin Inhibitor, Kunitz Soybean