SECONDARY MESSENGER Meaning and
Definition
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A secondary messenger is a crucial molecule involved in cellular signaling pathways that transmit and amplify signals from the cell surface to the interior of a cell. It acts as an intermediary or messenger between the primary extracellular signal and the intracellular targets. These molecules are involved in various cellular processes such as cell growth, differentiation, metabolism, and communication.
Secondary messengers are typically small molecules, such as cyclic adenosine monophosphate (cAMP), cyclic guanosine monophosphate (cGMP), inositol trisphosphate (IP3), and diacylglycerol (DAG). They are produced in response to the binding of a primary messenger, such as a hormone, neurotransmitter, or growth factor, to a specific receptor on the cell surface.
Once a secondary messenger is generated, it diffuses through the cytoplasm to activate or modulate downstream signaling cascades. These secondary messengers can activate protein kinases, ion channels, or other effector molecules, leading to a series of intracellular responses and ultimately influencing the behavior or function of the cell.
Secondary messengers play a crucial role in signal transduction, facilitating the integration and amplification of extracellular signals, and regulating complex cellular processes. They serve as key components in many physiological and pathological processes and are therefore important targets for pharmaceutical interventions in the treatment of various diseases, including cancer, diabetes, and neurological disorders.
Etymology of SECONDARY MESSENGER
The term "secondary messenger" is derived from the fields of biology and cell physiology. It refers to a molecule that transmits signals within a cell, typically after the initial signal is received by a cell surface receptor. These secondary messengers relay the signal from the receptor to different parts of the cell, often triggering a cascade of chemical reactions that ultimately result in a cellular response.
The word "secondary" in this context denotes that these messengers are not the primary molecule responsible for signal reception at the cell surface. Instead, they act as intermediaries in the cellular signaling pathway. They are "second" in the sequence of events, following the arrival of the primary signal.
The term "messenger" describes their role in transmitting or relaying the signal from one location to another within the cell. This concept is similar to how a messenger carries a message from one person to another.
