Signaling Pathways



In a multicellular organism, cell signaling pathways enable cells to communicate with each other to process information about the organism as a whole. Homeostasis is maintained because of specific receptors on the surface of and within cells, which are able to receive messages from other cells and make appropriate modifications. Receptors on the surfaces of cells include ion-channel receptors, G-protein-coupled receptors, and enzyme-coupled receptors, such as receptor tyrosine kinases (RTKs). Each receptor works to receive specific signals that tell the cells about changes within the organism. RTKs are a type of membrane receptor that influence the cell cycle among other functions. When these receptors fail, the cell can lose control of normal behaviors, including cell division, which can lead to cancer.

At A Glance

  • Cell-surface receptors receive messages that arrive on the outside surface of the cell membrane.
  • G-protein-coupled receptors receive signals that arrive on the cell membrane surface and are received by the G protein.
  • Ion-channel-coupled receptors are activated when ions bind with particular proteins on the cell membrane that have a complementary charge.
  • Receptor tyrosine kinases (RTKs) are a large and diverse group of enzyme-coupled receptors that activate many kinds of cellular events, including cellular growth and differentiation.
  • When signaling pathways that control cell division malfunction, a cell may divide uncontrollably, resulting in tumor formation.