signalmolekylene

Signalmolekylene are small molecules that mediate communication within and between cells and organisms. They are released by signaling cells and detected by target cells through specific receptors, triggering physiological or behavioral responses. Signalmolekylene regulate processes such as growth, metabolism, development, immune function, and behavior, and can act on local or distant targets depending on the signaling mode.

Signalmolekylene are often categorized by the spatial range of their action. Endocrine or hormonal signals travel through body fluids to distant sites; paracrine signals affect nearby cells; autocrine signals influence the same cell that released the molecule; and synaptic or neurotransmitter signals operate across synapses for rapid communication. Juxtacrine signals require direct cell-to-cell contact. Many signaling networks also involve environmental or social signals, such as pheromones released into the surroundings to influence other individuals.

The mechanism of action typically involves binding to specific receptors, which initiates signal transduction pathways. These pathways may activate enzymes, generate second messengers like cAMP or Ca2+, alter ion flux, or change gene expression. Signals can be amplified through cascades, producing timely and coordinated responses across tissues.

Signalmolekylene are central to biology across domains. In animals, examples include hormones like insulin and adrenaline, and neurotransmitters such as glutamate and dopamine. In plants, phytohormones like auxins, cytokinins, and ethylene coordinate growth and stress responses. In microbes, quorum-sensing signals regulate collective behaviors. Disorders of signaling pathways can contribute to diseases, while targeted signaling interventions underpin many therapies, agricultural practices, and biotechnologies.