Evolution of proteins of macroglobulin family

The first representatives of proteins of the macroglobulin family appeared 500-700 million years ago. At present representatives of this family have been revealed in crustaceans, molluscs, fish, amphibians, reptiles, ticks, insects, birds, and mammals, the macroglobulin family in blood of some species being represented simultaneously by several proteins that have different molecular weight and partly duplicate functions of each other. In different species, they are present as monomers, dimers, or tetramers. The distinguishing feature of each protein subunit is the presence of a "trap" with cyclic thioether on the bottom and of a sufficiently large hydrophobic area. All representatives are able to form complexes with different regulatory substances through covalent or hydrophobic bonds, which allows them to perform a wide range of regulatory functions. The ancient origin, evolutionary conservatism, widespread presence, and a diversity of regulatory functions permit proteins of the macroglobulin family to be considered as the main regulatory biomolecules of organism fluid media.