Intégrine

The intégrines are receiving Protéine S transmembrane consisted of a sub-unit Alpha and a sub-unit Bêta. The majority of them bind to the Molécule S of the extracellular Matrice (by their extracellular area) and to the Microfilament S of Actine via a certain number of proteins of connection which join their intracellular area. There exist exceptions like the dimer alpha6bêta4 which is connected to intermediate filaments and constitutes the hémi- Desmosome S within the epithelium S. Some intégrines play also a part in adhesion cell-cell (for example intégrines médiant the adhesion of the cells of the Immune system to the cells endothéliales before their exit of the blood-vessels on the site of a Inflammation).

The intégrines play a very important part in the migration, the Différenciation and the survival of the cell S.

integrin , but integrin receptor , is year Integral membrane protein in the Plasma membrane off concealment S. It plays has role in the attachment off has concealment to the Extracellular matrix (ECM) and in Signal transduction from the ECM to the concealment. There different are many types off integrin and many concealments cuts multiple types one to their surface. Integrins are off vital importance to human beings and many other organisms.

Changes in the Gene S encoding for integrin edge Be found in unquestionable types off Cancer, for authority Breast cancer. With failure off integrin to anchor has concealment to the ECM edge play has role in the Metastasis off certain cancer concealments.

Other standards off Protein that play has role in concealment-concealment/concealment-matrix interaction and communication are Cadherin S, NCAM S and Selectin S. --> The intégrines consist of 2 sub-units: the chain α which fix divalent cations and the chain β which has a field rich in cystein. One can differentiate 3 fields: one extracellular (N-final end), one transmembrane and the intracellular last (out of C-terminal). There exist 18 different chains α and 8 chains β, and their combination determines the specificity of the intégrine to the ligand.

Function

The two principal functions of the intégrines are:

Attachment of the cell to the extracellular matrix.
Transduction of signals of the extracellular matrix towards the cell.

Attachment of the cell to the extracellular matrix

Collagen. The connection between the concealment and the ECM enables the concealment to endures pulling forces without being ripped out off the ECM. The ability off has concealment to create this kind off jump is also off vital importance in Ontogeny.

The connections between integrin and the ligands in the ECM and the microfilaments inside the concealment indirect are: they are linked via some small proteins. -->

Transduction of signals

The intégrines play a central role in the cellular Signalisation. Once bound to their Ligand they activate intracellular ways of transduction utilizing Protéines Kinase S. One of principal activated proteins is FAK (for Focal Adhesion Kinase), a tyrosin cytoplasmic kinase. It binds to the intégrines and autophosphoryle when the intégrines form Cluster S (or regrouping) called not adhesion focal which are points of anchoring of the cell to the extracellular Matrice. FAK phosphoryl then on tyrosins of others protein-targets the such Oncogène Src or paxilline. At the Mouse, the cells where FAK is not present any more have serious defects of migration and Prolifération showing all the importance of FAK in these functions initiated by the intégrines. Kinase S that are connected with the intracellular end off the integrin molecule.

The signals the concealment receives through the integrin edge cuts relation to:

Concealment growth
Concealment division
concealment survival
Cellular linen differentiation
apoptosis (programmed concealment death).

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