Cadherins are also primarily responsible for the formation of stable junctions between cells in tissues. Tight junctions also separate apical from basolateral domains of the plasma membrane. Tight junctions are the closest known contacts between adjacent cells. Tight juctions appear to be formed by a network of protein strands that continues around the entire circumference of a cell. Each strand in this network seems to be composed of the transmembrane protein occludin .
Gap junctions serve as direct connection between cytoplasm of adjacent cells.
They provide open channels through plasma membranes, allowing ions and small molecules such as cAMP, to diffuse between neighboring cells. Thus Gap junctions couple metabolic activities and electric responses of cells they connect. Gap junctions are constructed from transmembrane proteins called connexins . In plants, adjacent cells communicate with each other through cytoplasmic connectins called plasmodesmata. The rigid cell walls of bacteria determine cell shape and prevent the cell from bursting as a result of osmotic pressure.