Signaalpathways

Signaalpathways, commonly known as signaling pathways, describe the organized sets of molecular interactions by which cells perceive and respond to their environment. They relay information from receptors on the cell surface or within organelles to intracellular targets, ultimately modulating gene expression, metabolism, growth, differentiation, or survival.

Core components include receptors, kinases and phosphatases, second messengers, scaffold and adaptor proteins, transcription factors, and ubiquitin or proteasome machinery that regulate turn-off. Signals are often amplified as they pass through cascades, and their outcomes are shaped by feedback loops and cross-talk with other pathways.

Examples of well-characterized pathways include MAPK/ERK, PI3K-AKT-mTOR, JAK-STAT, Notch, Wnt, Hedgehog, and TGF-β signaling. These networks can be linear or highly branched and may be initiated at the plasma membrane or within intracellular compartments. Spatial and temporal dynamics, such as localization and duration of signaling, are critical for specific responses.

Regulation occurs at multiple levels, including receptor activation, scaffold assembly, phosphorylation state, and degradation of signaling components. Dysregulation of signaling pathways is a common feature in diseases such as cancer, diabetes, and autoimmune disorders, making pathway components frequent therapeutic targets, notably receptor antagonists and kinase inhibitors.

Research approaches combine biochemistry, genetics, proteomics, phosphoproteomics, single-cell analysis, and computational modeling to map pathways and their interactions. Signaalpathways are evolutionarily conserved modules that support dynamic control of cellular behavior across diverse organisms.