ABSTRACT
This chapter discusses the general principles of cell communication. To make a multicellular organism, cells must communicate, just as humans must communicate if they are to organize themselves into a complex society. Just as human communication involves more than the passage of noises from mouth to ear, so cell–cell communication involves more than the transmission of chemical signals across the space between one cell and another. Communication between cells is mediated mainly by extracellular signal molecules. In contrast with other modes of cell signaling, gap junctions generally allow communications to pass in both directions symmetrically, and their typical effect is to homogenize conditions in the communicating cells. A different set of G-protein-coupled receptors acts in a similar way to mediate responses to pheromones, chemical signals detected in a different part of the nose that are used in communication between members of the same species.
