Signal transduction pathways function as biochemical communication networks wherein extracellular ligands bind to membrane receptors—specifically G-protein-coupled receptors (GPCRs), receptor tyrosine kinases (RTKs), or guanylyl cyclase—to initiate intracellular cascades. These mechanisms rely on distinct molecular switches: heterotrimeric G-proteins modulating adenylyl cyclase activity to generate cAMP, phospholipase C activation via the PLC-IP3-DAG-calcium pathway in specific subtypes, or RTK autophosphorylation triggering MAP kinase cascades (Ras-Raf-MEK-ERK). Additionally, nitric oxide regulates smooth muscle function through a simplified guanylyl cyclase-dependent cGMP-protein Kinase G axis.
Signal transduction pathways function as biochemical communication networks wherein extracellular ligands bind to membrane receptors—specifically G-protein-coupled receptors (GPCRs), receptor tyrosin…