Integrin alpha M
Encyclopedia
Integrin alpha M is one protein subunit that forms the heterodimeric integrin
alpha-M beta-2 (αMβ2) molecule, also known as macrophage-1 antigen (Mac-1
) or complement receptor
3 (CR3). ITGAM is also known as CR3A, and cluster of differentiation
molecule 11B (CD11B). The second chain of αMβ2 is the common integrin β2 subunit known as CD18
, and integrin αMβ2 thus belongs to the β2 subfamily (or leukocyte) integrins.
αMβ2 is expressed on the surface of many leukocytes involved in the innate immune system
, including monocyte
s, granulocyte
s, macrophage
s, and natural killer cell
s. It mediates inflammation by regulating leukocyte adhesion
and migration and has been implicated in several immune processes such as phagocytosis, cell-mediated cytotoxicity, chemotaxis
and cellular activation. It is involved in the complement system
due to its capacity to bind inactivated complement component 3b (iC3b). The ITGAM (alpha) subunit of integrin αMβ2 is directly involved in causing the adhesion and spreading of cells but cannot mediate cellular migration without the presence of the β2 (CD18) subunit.
In genomewide association studies, single nucleotide polymorphisms in ITGAM had the strongest association with systemic lupus erythematosus
, with an odds ratio of 1.65 for the T allele of rs9888739 and lupus.
Integrin
Integrins are receptors that mediate attachment between a cell and the tissues surrounding it, which may be other cells or the ECM. They also play a role in cell signaling and thereby regulate cellular shape, motility, and the cell cycle....
alpha-M beta-2 (αMβ2) molecule, also known as macrophage-1 antigen (Mac-1
Mac-1
MAC-1 may refer to:* Macrophage-1 antigen* Integrin alpha M...
) or complement receptor
Complement receptor
A complement receptor is a receptor of the complement system, a part of the mediated innate immune system. Complement receptors are responsible for detecting pathogens by mechanisms not mediated by antibodies. Complement activity is not antigen sensitive, but can be triggered by specific antigens...
3 (CR3). ITGAM is also known as CR3A, and cluster of differentiation
Cluster of differentiation
The cluster of differentiation is a protocol used for the identification and investigation of cell surface molecules present on white blood cells, providing targets for immunophenotyping of cells...
molecule 11B (CD11B). The second chain of αMβ2 is the common integrin β2 subunit known as CD18
CD18
Integrin beta-2 is a protein that in humans is encoded by the ITGB2 gene.It is the beta subunit of four different structures:* LFA-1 * Macrophage-1 antigen * Integrin alphaXbeta2...
, and integrin αMβ2 thus belongs to the β2 subfamily (or leukocyte) integrins.
αMβ2 is expressed on the surface of many leukocytes involved in the innate immune system
Innate immune system
The innate immune system, also known as non-specific immune system and secondary line of defence, comprises the cells and mechanisms that defend the host from infection by other organisms in a non-specific manner...
, including monocyte
Monocyte
Monocytes are a type of white blood cell and are part of the innate immune system of vertebrates including all mammals , birds, reptiles, and fish. Monocytes play multiple roles in immune function...
s, granulocyte
Granulocyte
Granulocytes are a category of white blood cells characterized by the presence of granules in their cytoplasm. They are also called polymorphonuclear leukocytes because of the varying shapes of the nucleus, which is usually lobed into three segments...
s, macrophage
Macrophage
Macrophages are cells produced by the differentiation of monocytes in tissues. Human macrophages are about in diameter. Monocytes and macrophages are phagocytes. Macrophages function in both non-specific defense as well as help initiate specific defense mechanisms of vertebrate animals...
s, and natural killer cell
Natural killer cell
Natural killer cells are a type of cytotoxic lymphocyte that constitute a major component of the innate immune system. NK cells play a major role in the rejection of tumors and cells infected by viruses...
s. It mediates inflammation by regulating leukocyte adhesion
Cell adhesion
Cellular adhesion is the binding of a cell to a surface, extracellular matrix or another cell using cell adhesion molecules such as selectins, integrins, and cadherins. Correct cellular adhesion is essential in maintaining multicellular structure...
and migration and has been implicated in several immune processes such as phagocytosis, cell-mediated cytotoxicity, chemotaxis
Chemotaxis
Chemotaxis is the phenomenon in which somatic cells, bacteria, and other single-cell or multicellular organisms direct their movements according to certain chemicals in their environment. This is important for bacteria to find food by swimming towards the highest concentration of food molecules,...
and cellular activation. It is involved in the complement system
Complement system
The complement system helps or “complements” the ability of antibodies and phagocytic cells to clear pathogens from an organism. It is part of the immune system called the innate immune system that is not adaptable and does not change over the course of an individual's lifetime...
due to its capacity to bind inactivated complement component 3b (iC3b). The ITGAM (alpha) subunit of integrin αMβ2 is directly involved in causing the adhesion and spreading of cells but cannot mediate cellular migration without the presence of the β2 (CD18) subunit.
In genomewide association studies, single nucleotide polymorphisms in ITGAM had the strongest association with systemic lupus erythematosus
Systemic lupus erythematosus
Systemic lupus erythematosus , often abbreviated to SLE or lupus, is a systemic autoimmune disease that can affect any part of the body. As occurs in other autoimmune diseases, the immune system attacks the body's cells and tissue, resulting in inflammation and tissue damage...
, with an odds ratio of 1.65 for the T allele of rs9888739 and lupus.
Further reading
External links
- Mouse CD Antigen Chart
- Human CD Antigen Chart
- ITGAM Info with links in the Cell Migration Gateway