Signal Transduction

Signal transduction is a physiological process which enables communication between cells and inside them. It allows the organism to adapt to external and internal events. This process is regulated through cascades of molecular changes such as phosphorylation of proteins thanks to kinases. Stimuli are taken into account thanks to receptors which can go through conformational changes or biochemical reaction upon ligand binding for example.
The response of such a cascade can result in gene transcription or translation variation, protein post-translational modifications and localization, enzyme or ion-channel activation. Signal transduction impacts on many biological pathways such as metabolism, cell development and proliferation.
Proteogenix offers proteins involved in signal transduction to help research extend on the different signal pathways.

Signal transduction may be stimulated by several types of events. Ligand binding is a classical cell signaling method. As many ligands are soluble in the extracellular medium, receptors may be observed at the surface of the cells. These receptors may be bound covalently with enzymes that activate upon ligand binding. They can also activate second messengers such as AMP via adaptor proteins and enzymes. Receptors are also found inside cells and studied in cell biology for their reactivity.
Other stimuli as mechanical forces, osmolarity, temperature and light are detected and induce responses through a set of proteins such as integrins, actin, transient receptor potential channels and melanopsin for example.

G-Protein Coupled receptors (GPCR) are a class of transmembrane receptors with seven transmembrane domains and one heterotrimeric G protein. Upon ligand binding, the G protein is activated to form a GTP molecule from a GDP. GTP will then dissociate to be used in downstream cascade. They include receptors of light sensitive molecules, hormones, pheromones and neurotransmitters. They are involved in cAMP and phosphatidylinositol signal pathways. GPCR are often targeted in therapies as they are involved in many diseases from cancer to cardiovascular and immunology disorders or viral infection.

The Toll-like receptors (TLR) are a family of receptors found in innate immunity recognition cells such as macrophages. They are responsible for the recognition of antigens and further activation of the immune system.