Information on the properties of proteins of the macroglobulin family taking part in the host protection from viral, fungal and bacterial pathogens is reviewed. High plasticity and polyfunctional character of these proteins makes it possible to realize different protective functions. They inhibit the lysis of the cell wall by binding the hydrolases of the pathogen thus blocking its penetration into the cell, directly participate in the presentation of antigens to immunocompetent cells, transport antibacterial substances (interferons, lysozyme) to the zone of infection. In addition, macroglobulins take part in the apoptosis regulation in infected cells, utilization of the lysosomal enzymes of annihilated pathogens. The complexes of macroglobulins with some proteins are powerful inductors of antibody production. Further studies of the properties of these proteins will result in a better understanding of the nature of infectious process. The possibility of artificial formation of macroglobulin complexes with pathogen components or with substances possessing protective or anti-inflammatory properties opens prospects for using these proteins in the fields of vaccinology, gene therapy and molecular biology.

Animals↗

PubMedDate not supplied

[Role of proteins of the macroglobulin family in regulation of tumor growth].

Proteins of the macroglobulin family are an ancient and evolutionarily conservative link of the immune system, which is actively involved in both inhibition of tumor growth cells and proliferation of tumor cells. Two basically different binding sites and a great conformational plasticity of all representatives of the macroglobulin family, as well as the presence of two to four representatives of the family in the blood of most species allow them to transport diverse substances and exert various regulatory influences on both the tumor and the entire organism. For example, the capacity of macroglobulins for binding hydrolases makes it possible to inhibit enzyme mediated tumor invasion. At the same time, an excess of macroglobulin/hydrolase complexes can activate apoptosis. The tumor is able of using macroglobulins, especially pregnancy-associated proteins, for its own protection. Specifically, pregnancy-associated alpha2-glycoprotein, which is actively produced by human tumor cells, blocks the histocompatibility complex antigens. On the contrary, the capacity of binding zinc stimulates the thymulin-dependent activation of natural killer cells. Nevertheless, the actively growing tumor expresses many receptors to macroglobulins, which are the main carriers of some cytokines and growth factors essential for proliferation.

Animals↗

PubMedDate not supplied

[Macroglobulin protein family evolution].

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Animals↗

PubMedDate not supplied

[Specific reactions of polyfunctional proteins of the family of macroglobulins and lactoferrin with receptors and ligands in the protection of the body from pathogens].

The reactions of polyfunctional proteins alpha2-macroglobulin (MG) and lactoferrin (LF) lipoprotein-receptor protein (LRP) and different ligands (antibodies and hydrolases) for ascertaining the mechanisms of their interaction and the probable role of MG and LF in the neutralization of bacterial pathogens were under study. The binding of MG and LF with ligands, irrespective of their nature, was shown to lead to the neutralization of the complex thus formed. This mechanism of neutralization in reaction of LF with ligands was supposedly due to the antibacterial properties of this protein: multiple reactions of LF with receptor sites on the surface of pathogens neutralized the charge of the latter and facilitated phagocytosis. The interaction of LRP of immunocompetent cells with MG, in the presence of additional binding sites on its surface, made it possible for MG to effectively bind and present even heretofore unknown pathogens in the presence of hydrolases on their surface.

Chemical Precipitation↗

PubMedDate not supplied

[The role of macroglobulin family proteins in the regulation of inflammation].

The macroglobulin family represents a group of universal regulators involved into control of the inflammatory response to external and internal pathogens. Alpha-2-macroglobulin (MG), the major protein in the family, has 3 different binding sites and high affinity to an endocytosis receptor that allows MG to participate in recognition and phagocytosis of the foreign agents. The macroglobulin family proteins are most powerful apoptosis inhibitors: they bind autoaggressive hydrolases accumulating during inflammation. MG is the main transporter of cytokines and growth factors controlling the inflammatory response. At the same time, the macroglobulins are negative reactants of an acute phase of inflammation and the decrease of their synthesis at later stages is necessary for stimulation of collagenosis processes, coagulation, activation of thymulin, stimulating NK. At septic inflammation binding of macroglobulins to exotoxins can localize inflammation, and initiate systemic inflammatory response. Macroglobulin damage sharply reduces their subsequent utilization; this provokes accumulation of makroglodulin-proteinase complexes in biological fluids and may cause immune inflammation.

Apoptosis↗

PubMedDate not supplied

[A comparative study of the physicochemical and antigenic properties of human and animal albumins].

Studies have been made on physico-chemical and antigenic properties of albumins from man, mammals, birds, insects, amphibians, worms, fishes and crustaceans. It was found that all the animals contain structurally identical proteins with similar physico-chemical properties. At the same time, the level of antigenic identity of the proteins decreases in the following order: type, genus, family, species.

Amphibians↗