Cell membrane Adhesiveness

The completed exopolysaccharide is then transported to the cell surface through membrane adhesion zones. 

The basement membrane is a structure that supports overlying epithelial or endothelial cells. The primary fimction of the basement membrane is to anchor down the epithelium to its loose connective tissue underneath. This is achieved by cell-matrix adhesions through cell adhesion molecules. 

Ras is a G protein that cycle between two conformations, an activated Ras-GTP or inactivated form Ras-GDP. Ras, attached to the cell membrane by lipidation, is a key component in many signalling cascades, which couple growth factor receptors to downstream effectors that control such processes as cytoskeletal integrity, proliferation, cell adhesion, apoptosis and cell migration. Mutations and dysregulations of the Ras protein leading to increased invasion and metastasis, and decreased apoptosis are very common in cancers. 

It has been shown that cell adhesion highly depends on the outermost functional groups on SAMs however, cells do not directly interact with the SAMs. Instead, they interact with proteins adsorbed on SAMs. Cell adherence requires an interaction between integral molecules in the cell membrane and glycoproteins specialized for cell adhesion, like fibronectin (Fn) and vitronectin (Vn), which are adsorbed on the artificial material. Thus, the presence of glycoproteins in serum plays a crucial role in cell adherence to artificial materials. In the first part of this review (Sect. 2), we will briefly survey recent studies of cell adhesion on SAMs with different functional groups and discuss the mechanisms involved. 

Fig. 1 Real-time tracking of cell adhesion [42]. (a) Components of a total internal reflection fluorescent microscope (TIRFM). (b) The cell adhesion process (7) a cell approaches the surface, (2) the cell lands, (3) the cell attaches, and (4) the cell spreads out on the surface. The evanescent field was generated by total internal reflection of a laser beam at the glass-water interface. Cells with fluorescently labeled membranes (dashed lines) were plated on SAMs. Cell membranes within the evanescent field (solid line) were observed by TIRFM. Corresponding TIRFM images are shown below...

We assembled a TIRFM with low magnification to study cell adhesion behavior on SAMs with various functional groups [42]. Figure lb shows a schematic illustration of the cell adhesion process and the corresponding TIRFM images. A suspension of cells with fluorescently labeled cell membranes is applied onto a substrate (Fig. lb-1). At first, no bright spots were observed by TIRFM,... 

Adhesion molecules are indispensable components of nervous tissue. They adhere cell membranes to each other with varying degrees of strength and translate adhesion into cellular responses via signal-transduction pathways (see, for example, [45]). The major classes of adhesion molecules, the integrins, IgCAMs and cadherins, act cooperatively [46] and in concert to coordinate brain development and maturation and, in adulthood, to maintain the normal tissue architecture. 

Adhesion proteins in this group contain an immunoglobulin domain that is composed of 90-100 amino acids arranged in a sandwich of two sheets of antiparallei strands. Some members of this family also contain fibronectin type III—like domains in addition to the immunoglobulin domain. Immunoglobulin-related adhesion proteins either can exist as transmembrane structures or can be attached to cell membranes via glycosyl phosphatidylinositol links (B4, R5). 

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