Sekundärmessengerstoffe

Sekundärmessengerstoffe, also known as second messengers, are small intracellular molecules that transmit signals from cell surface receptors to intracellular targets. These molecules are crucial components of cellular signal transduction pathways, allowing cells to respond to external stimuli. When a primary messenger, such as a hormone or neurotransmitter, binds to its receptor on the cell surface, it often triggers the activation of enzymes that generate or release secondary messengers within the cell.

Common examples of secondary messengers include cyclic adenosine monophosphate (cAMP), cyclic guanosine monophosphate (cGMP), inositol trisphosphate (IP3), diacylglycerol (DAG), and calcium ions (Ca2+). These molecules can then activate a variety of downstream effectors, such as protein kinases or ion channels, which ultimately lead to a specific cellular response. This response can range from changes in gene expression and protein synthesis to alterations in cellular metabolism and motility. The amplification of the initial signal is a key feature of secondary messenger systems, as a single receptor activation can lead to the production of many second messenger molecules, thus generating a strong cellular response. The precise nature of the cellular response depends on the type of cell and the specific signal transduction pathway involved.