signaalinvälitysketju

Signaalinvälitysketju, known in English as signal transduction pathway, is a series of molecular events that occurs inside a cell to transmit a signal from the cell surface to the inside of the cell, ultimately leading to a cellular response. These pathways are crucial for cells to perceive and respond to their environment, enabling processes like growth, differentiation, and adaptation to stimuli.

The process typically begins when a signaling molecule, such as a hormone or neurotransmitter, binds to a specific receptor protein on the cell membrane. This binding event triggers a cascade of intracellular events. Often, this involves a series of protein phosphorylations and dephosphorylations, where phosphate groups are added or removed from proteins, altering their activity. These changes propagate the signal through a chain of intermediary molecules.

Eventually, the signal reaches its target, which might be a transcription factor that alters gene expression, an enzyme that initiates a metabolic pathway, or a component of the cytoskeleton that changes cell shape. The specific molecules involved and the sequence of events vary greatly depending on the cell type and the nature of the original signal.

Signaalinvälitysketjut are highly regulated to ensure appropriate cellular responses. Errors in these pathways can lead to various diseases, including cancer and metabolic disorders, highlighting their fundamental importance in cellular function and organismal health. The study of these pathways is a major area of biological research, aiming to understand complex cellular processes and develop targeted therapies.