User:Gillotam/sandbox

Cell-cell recognition occurs when two molecules restricted to the plasma membranes of different cells bind to each other, triggering a response for communication, cooperation, transport, defense, and/or growth. Rather than induce a distal response, like secreted hormones may do, this type of binding requires the cells with the signalling molecules to be in close proximity with each other. These events can be grouped into two main categories: Intrinsic Recognition and Extrinsic Recognition[3]. Intrinsic Recognition is when cells that are part of the same organism associate[3]. Extrinsic Recognition is when the cell of one organism recognizes a cell from another organism, like when a mammalian cell detects a unicellular microorganism in the body[3]. The molecules that complete this binding consist of proteins, carbohydrates, and lipids, resulting in a variety of glycoproteins, lipoproteins, and glycolipoproteins[3]. The binding event itself can be between a number of combinations of molecule types. For instance, proteins bind to glycans to trigger events in immune response and cell adhesion with leukocytes and platelet cells.[3].Studies suggest glycan- glycan interactions, observed to be approximately 200-300pN, also may play a role in cell- cell recognition. Complex carbohydrates, in particular, have been studied to be extremely integral in cell-cell recognition, especially when it is recognized by complementary carbohydrates. In order to ensure a proper binding site by checking the surrounding areas or securing a bond that was previously made complex carbohydrates and their complementary carbohydrates are able to create flexible interaction systems. These interactions, although observed to be weak, have been studied in a variety of test subjects including, but not limited to, mouse embryonal cells, corneal epithelial cells, and human embryonal carcinoma cells.