Signaling Transduction can also be called cell signaling. Signaling Transduction is the transmission of signals from the outside to the inside of a cell. The signals recieved by cells must be transmitted effectively into the cell to ensure an appropriate response. The most common form is protein phosphorylation. Signal transducing receptors are of four general classes:
Receptors that penetrate the plasma membrane and have intrinsic enzymatic activity or are enzyme associated (Enzyme-linked Receptors)
Receptors that are coupled, inside the cell, to G proteins (7-TM Receptors)
Receptors that are found intracellularly and upon ligand binding directly alter gene transcription (Nuclear Receptors)
phosphorylation alters the structural conformation of a protein, causing it to become activated, deactivated, or modifying its function. Protein kinases and phosphatases work independently and in a balance to regulate the function of proteins.
Major Pathways
MAPK Pathway This pathway couples intracellular responses to the binding og growth factors to cell surface receptors. It is a very complace pathway that includes many proteins. cAMP-dependent Pathway Works by activating protein kinase IP3/DAG Pathway calcium and DAG together works to activate PKC, which goes on to phosphorylate other molecules, leading to altered cellular activity