Molecular Biology of the Cell - Volume 2 - Alberts B., Bray D., Lewis J., Raff M., Roberts K., Watson J. 1993

Intercellular signaling

Cells of a multicellular Organism need to exchange information with one another to regulate their development and tissue Organization, control growth and division processes, and coordinate their Functions. Animal cells communicate in three ways: 1) cells secrete chemical substances that act as signals for other cells located at a distance; 2) they carry Cell/33.html">Plasma Membrane-bound signaling molecules on their surface that influence other cells through direct physical contact; 3) they form Gap Junctions that directly connect the cytoplasms of two interacting cells, enabling the exchange of small molecules (Fig. 12-1).

Cell interaction via gap junctions will be discussed in Chapter 14, but here we focus primarily on long-distance communication mediated by secreted chemical signals. This organization reflects the Current state of knowledge in the field. Secreted molecules are incomparably easier to study than membrane-bound ones, and much is already known about their Mechanisms of action. Contact-dependent signaling via cell-surface molecules is significantly more challenging to detect and is therefore much less understood; however, it is also vital, particularly in developmental processes and the Immune Response (Section 18.6.1), and its molecular basis appears to be quite similar to that of long-range signaling. The Specific features of CHEMICAL SIGNALING IN The Nervous system and the unique principles governing plant signaling will be covered separately in Chapters 19 and 20, respectively.

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Fig. 12-1. Three different modes of intercellular chemical signaling.