Compare and Contrast The Structure And Function Of Intercellular Junctions
Intercellular Junctions are places where cells come into contact with each other, usually formed by proteins in the plasma membrane. There are four main types of intercellular junctions in vertebrates: gap junctions, tight junctions and anchoring junctions (adherens junctions and desmosomes) (1). Each one has differences and similarities to other junctions.
Differences in the Functions of intercellular junctions
Each type of junction has clear differences in function. Gap junctions, types of communicating junction, and tight junctions, the main type of occluding junction, both affect the movement of molecules and ions, although in very different ways and different places (1,2,5). The other junctions, the anchoring junctions, have very dissimilar roles to tight and gap junctions as they are not involved in the movement of substances but mainly allow for cellular adhesion (1,4).
Gap junctions provide a channel between two cells and allow the transport of messengers (eg cAMP) and ions (eg K+ and Ca2+) between cells. This can be controlled by changes to factors like the pH or the concentration of Ca2+, which affect the protein kinases necessary to modify the connexins to allow them to open and close…show more content… The proteins involved in these junctions, called conexins, form cylinders called conexons, with each cylinder containing 6 conexins. Molecules and ions are only able to move through the gap junctions when conexons align, causing a connection between the cytoplasm of the two cells as shown in figure 2 (Bloomfield SA, Völgyi B 2009). The pore that is created in the middle of the conexons makes the structure of these junctions different from the other intercellular junctions as all the other junctions only provide a connection to another protein to allow for there function, whereas gap junctions provide passages from the cytoplasm of one cell to the other