Chemical-signaling molecule

The intracellular activation of enzymes in a signaling chain can lead to the formation of diffusible chemical signaling molecules in the cell. These intracellular signaling molecules are also termed second messengers. The second messenger molecules activate and recruit cognate enzymes for the further signal transduction. 

Chemical Signal Molecule for Vesicular Arbuscular Mycorrfaiza (VAM)... 

Cellular functions are controlled by extracellular signals such as hormones, neurotransmitters, odorants, light and other chemical or physical stimuli. Only a few of these signal molecules, e.g., the highly lipid-soluble steroids or thyroid hormones, can diffiise across the... 

While the mammals predominate in their integration and representation of the sensory world, their noses still tell the brain directly about its chemical space. To explain the workings of accessory olfaction, we need to trace the path of a signal molecule from the moment it leaves its source until a response occurs in the recipient. The events which occur en route will determine the effectiveness of the intended communication. 

---