CELL ADHESION MOLECULES

CELL ADHESION MOLECULESINTRODUCTIONCell adhesion molecules are proteins located at the cell surface involved in binding with other cells or with the extracellular matrix( ECM) in the process called cell adhesion. Cell adhesion molecules help cells stick to each other and their surroundings. Cell adhesion

Cell adhesion proteins are typically transmembrane receptors and are composed of three domains:An intracellular domain; that interact with the cytoskeletonA transmembrane domainAn etxtracellular domain; that interact with either other CAMs of the same kind(homophilic binding) or with other CAMs or the extracellular matrix(heterophilic binding).

Intro continues.Embryonic development; formation of layers, tubesFormation of the nervous system and other tissuesHolding tissues together in adultsInflammationWound healingMetastasis of tumorsImportance of CAMsCAMs can be divided into four broard families:CadherinsIntegrinsSelectinsAdhesion molecules of the IgG superfamily of immunoglobulineFamilies of CAMs

CAMs

cadherinsCadherins are calcium dependent molecules that mediate cell to cell adhesion by homophilic reactions. They form adherens junctions that bind cells within tissues together. Cadherins are important in formation of nervous system and other tissues; responsible for separation of different tissue layers and for cellular migration during embryonic development. After development they play a role in maintaining cell and tissue structure, and in cellular movement.Cont.

cadherins allow cells to sort themselves

Integrins are heterodimers that bind to various receptors, whose ECM partner molecules include; collagen,laminin and fibronectinHeterophilic connection/binding They are transmembrane receptors that are the bridges for cell to cell and cell to extracellular matrix interactions. Their role is to provide attachment of the cell to the extracellular matrix, as well as signal transduction from the extracellular matrix to the cellintegrinsAll selectins are single chain transmembrane glycoproteins that bind to sugar moieties and so are considered to be a type of lectin, cell adhesion proteins that bind sugar polymers.Selectins are involved in constitutive lymphocyte homing , and in chronic and acute inflammation processesselectinsImmunoglobulin superfamily is a large group of cell surface and soluble proteins that are involved in the recognition, binding, or adhesion processes of cells.Homophilic binding typicalHeterophilic binding rare Linked to actin filamentsExpressed in the critical phase of developmentTissue-specificity; epithelial, lymphoid, placentaImmunoglobululin superfamily(IgSF)Barrett k, et al (2010), Ganongs Review of Medical Physiology, 23rd Edition, McGraw-Hill companies, inc. USAReferrences