What is the Origin of Molecular Messenger Action?

This concept is foundational to pharmacology and endocrinology, originating with the Lock-and-Key model of receptor binding and the subsequent elucidation of second messenger systems. 'Molecular Messenger' describes the role of the hormone or signaling molecule as a carrier of information, and 'Action' refers to the resultant physiological effect. The understanding of this process has been refined by the discovery of various receptor types, including cell-surface and intracellular receptors.

What is the Mechanism of Molecular Messenger Action?

The action begins when the molecular messenger, often a steroid or peptide hormone, travels through the circulation and binds to its specific receptor on the target cell. For steroid hormones, the messenger typically enters the cell and binds to an intracellular receptor, forming a complex that then modulates gene transcription in the nucleus. For peptide hormones, binding to a cell-surface receptor activates secondary messengers, such as cyclic AMP or calcium ions, which rapidly transduce the signal to alter enzyme activity or cellular permeability.

Molecular Messenger Action ∞ Area

Molecular Messenger Action

Meaning

Molecular Messenger Action refers to the process by which specific signaling molecules, including hormones, neuropeptides, and neurotransmitters, bind to their corresponding cellular receptors to initiate a cascade of intracellular events that alter cell function. This action is the fundamental mechanism of communication within the endocrine and nervous systems, translating an external or systemic signal into a precise biological response, such as gene expression or enzyme activation. The efficiency of this action is dependent on receptor density and ligand affinity.