What role do cell membrane receptors play in cell signalling?

The Plasma Membrane consists of phospholipid bilayer with integral proteins, glycoproteins, transport proteins and globular protein. As part of the phospholipid bilayer there are cell surface receptors. The receptors bind complimentary to the signaling molecule, however receptors for steroid molecules can pass through the phospholipid bilayer to receptor molecules within the cytoplasm. Cell surface receptors when bound by a complimentary molecule will undergo a complimentary change. For example receptor tyrosine kinases undergo dephosphorylation on the internal side of the receptor which leads to  phosphorylation of P13K. P13K then undergoes a conformational change which leads to phosphorylation of AKT. AKT can lead to Transcription of specific proteins from DNA within the nucleus that may cause cell proliferation, survival and differentiation. The main role of receptors is to respond to a increase of the specific signaling molecule.

The cell membrane receptors receive the signal from the environment of the cell and convey the signal to the nucleus in the cell. The cell will interpret the signal and perform the required actions through signaling processes.

Cell membrane receptors can bind to an array of molecules most common example being proteins. This protein-receptor interaction can trigger several downstream signalling pathways for the purpose of intercellular communication, delivery of proteins, drugs, RNA into or between cells, synthesis of other molecules required for cell survival.

Cell membrane receptors change their structural confirmation when a molecule binds, which in the case of G-protein coupled receptors, causes uncoupling of a G protein to cause downstream signalling within the cell (for example, ATP conversion to cAMP, which activates protein kinase A). Therefore cell membrane receptors are required to initiate cell signalling.

Cell membrane receptors play differing roles in cell signalling. Receptors usually have unique shapes that are complementary to the Ligand that binds to this. The ligand could be a hormone, it could be a pharmaceutical drug that has been manipulated to have the specific shape. Upon binding a conformational change to the receptor usually occurs, opening or closing a channel or leading to the activation of another protein. . This can be followed a series of reactions can occur such as increasing the concentration of ions, increasing the concentration of second messenger molecules. These can act as transcription factors to transcribe specific proteins.

cells are able to communicate across distances within the body using this method.

Cell membrane receptors also act as antigens in the immune system. This is how some pathogens can entry into host cells. They are able to bind to cell membrane receptors to cause a chain of events that leads to endocytosis or access through membrane channels.

Cell membrane receptors will bind to hormones released by other cells. This binding will cause the receptors to change shape, this change in shape will result in changes within the cells. These changes in the cell are therefore are a response to the signall (the hormone)