5 CHEMICAL MESSENGERS
Mechanisms of Intercellular Communication
DIRECT COMMUNICATION THROUGH GAP JUNCTIONS
Gap junctions link adjacent cells, and are formed by plasma membrane proteins, called
connexins, that form structures called connexons.
The movement of ions through gap junctions electrically couples the cells, such that electrical
signals in one cell are directly transmitted to the neighboring cells.
INDIRECT COMMUNICATION THROUGH CHEMICAL MESSENGERS
Ligands: chemical messengers, molecules that bind to proteins.
A target cell responds to the chemical messenger because it has certain proteins (receptors).
Signal transduction: the binding of messengers to receptors produces a responds in the target
cell through mechanisms.
The strength of the target cell response increases as the number of bound receptors increases.
Depends on concentration of messengers and receptors.
FUNCTIONAL CLASSIFICATION OF CHEMICAL MESSENGE