Signal Transduction Mechanism:A Critical Review

Cellular signaling plays an important role in alteration of cellular physiology and initiation of pharmacological response. Cells usually communicate with each other through extracellular messenger molecules called ligand which can travel a short distance and stimulate cells with the release of second messenger molecule by a cell that is engaged in sending messages to the downward in same cell or to the other cells in the body. Cells can only respond to a particular extracellular message if they express receptors for that ligand specifically recognize and bind that messenger molecule and the interaction between the ligand and receptor induces a conformational change in the receptor that causes the signal to be relayed across the membrane to the receptor’s cytoplasmic domain. A signaling pathway is activated by a diffusible second messenger and another in which a signaling pathway is activated by recruitment of proteins to the plasma membrane. Most signal transduction pathways involve a combination of these mechanisms. In this review we have tried to elaborate diagrammatically the details about the various pathways responsible for signaling for easy understanding for the future research.