Juxtacrine signaling is a mode of cell signaling in which the signaling molecules are directly transferred from one cell to another through physical contact. This type of signaling requires close proximity between the signaling and target cells, as the signaling molecules are unable to diffuse through the extracellular space.
In juxtacrine signaling, the signaling molecule is typically a membrane-bound protein or ligand on the surface of the signaling cell. When the signaling cell comes into contact with the target cell, the membrane-bound molecule binds to a receptor on the surface of the target cell, triggering a cellular response.
This mode of signaling is important for processes such as cell adhesion, cell migration, and immune responses. Juxtacrine signaling allows for precise and localized communication between cells, ensuring that the signaling molecules only affect the target cells with which they come into direct contact.
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Google Gemini AI
May 25
Juxtacrine Signaling
Juxtacrine signaling, also known as direct cell-cell signaling, is a mode of intercellular communication that occurs when two cells are in close physical contact. The molecules involved in juxtaposition signaling are typically membrane-bound proteins that interact with their cognate receptors on the surface of neighboring cells.
Mechanism:
- Juxtacrine signaling is mediated by the interaction of transmembrane proteins expressed on the surfaces of adjacent cells. - These proteins can be ligands or receptors, depending on their cellular location. - Upon binding, these proteins form a complex that triggers intracellular signaling pathways in both cells.
Types of Interactions:
- Cell-cell adhesion molecules (CAMs): CAMs mediate the initial adhesion of cells to each other, forming a stable intercellular junction. Examples include cadherins, integrins, and selectins. - Ligand-receptor interactions: Ligand-receptor interactions are typically one-to-one interactions where a soluble ligand binds to a specific receptor on the target cell's surface. In juxtacrine signaling, these interactions involve membrane-bound ligands and receptors. - Direct protein-protein interactions: Juxtacrine signaling can also involve direct protein-protein interactions between non-receptor proteins on adjacent cells.
Examples:
- Notch signaling: Notch is a transmembrane protein that plays a crucial role in cell fate determination and differentiation. It signals through direct interaction with its ligand Delta or Serrate, which are expressed on neighboring cells. - Ephrin signaling: Ephrins are membrane-bound ligands that interact with Eph receptors on neighboring cells. Ephrin-Eph interactions regulate cell migration, axon guidance, and cell-cell repulsion.
Significance:
Juxtacrine signaling plays a vital role in various biological processes, including:
- Cell adhesion and tissue morphogenesis - Cell fate determination and differentiation - Axon guidance and synapse formation - Immune responses - Cancer cell growth and metastasis