Viestintämolekyylit

Viestintämolekyylit, also known as signaling molecules or chemical messengers, are substances produced by cells in an organism that are used to transmit information between cells. This intercellular communication is crucial for coordinating the activities of cells, tissues, and organs, enabling the organism to respond to its environment and maintain homeostasis.

These molecules can be broadly categorized based on their origin and target. Endocrine signaling involves hormones secreted by endocrine glands directly into the bloodstream, which then travel to distant target cells throughout the body. Paracrine signaling occurs when a cell releases a signaling molecule that acts on nearby neighboring cells. Autocrine signaling is a special case where a cell releases a molecule that binds to receptors on its own surface, thereby regulating its own behavior. Juxtacrine signaling requires direct contact between two cells, where signaling molecules on the surface of one cell bind to receptors on the surface of another.

The process of cell signaling typically involves three key steps: reception, transduction, and response. First, the signaling molecule (ligand) binds to a specific receptor protein on the target cell. This binding event triggers a cascade of intracellular events, known as signal transduction, which amplifies and relays the signal. Finally, the transduced signal leads to a specific cellular response, which can include changes in gene expression, enzyme activity, ion channel permeability, or cell division. Examples of viestintämolekyylit include hormones like insulin and adrenaline, neurotransmitters like acetylcholine and dopamine, and growth factors.