What is the Difference Between Juxtacrine and Paracrine

The main difference between juxtacrine and paracrine is that juxtacrine signaling requires close contact of cells or cells with the extracellular matrix, whereas paracrine signaling produces signals that induce changes in nearby cells.

Juxtacrine and paracrine are two types of cell signaling methods. Cells undergo cell signaling that is important in development, tissue repair, immunity, and homeostasis.  

Key Areas Covered

1. What is Juxtacrine Signalling
– Definition, Features, Importance
2. What is Paracrine Signalling
– Definition, Features, Importance
3. Similarities Between Juxtacrine and Paracrine Signalling
– Outline of Common Features
4. Difference Between Juxtacrine and Paracrine Signalling
– Comparison of Key Differences

Key Terms

Juxtacrine Signalling, Paracrine Signalling

What is Juxtacrine Signalling

Juxtacrine signaling is a method of signaling that is contact-dependent. Therefore, it requires a cell-to-cell or cell-to-extracellular matrix in close contact for signaling. In juxtacrine signaling, a ligand on one surface binds to the receptor of another surface. On the other hand, there are three types of juxtacrine signaling methods. The first type is the membrane-bound ligand, such as a protein, oligosaccharide, or lipid, and a membrane protein of two adjacent cells in contact. The second type is a communicating junction that links two intracellular compartments of adjacent cells allowing the transit of small molecules. The third type is extracellular matrix glycoprotein and membrane protein interactions.

Figure 1: Juxtacrine Signalling

Furthermore, unicellular microorganisms interact by membrane contact is an example of juxtacrine signaling.  

What is Paracrine Signalling

Paracrine is another type of cell signaling in which signaling molecules diffuse to the cells that are in close proximity to the cells of production. This means the target cells are nearby cells, and the diffusion of paracrine molecules occurs through the extracellular matrix. Due to the short distance between the target and the cells of production, paracrine signaling takes a short time to reach the target when compared to endocrine signaling, which diffuses through the bloodstream. Moreover, since the paracrine signal has to be localized, the paracrine signaling molecules are quickly degraded by enzymes.

Figure 2: Paracrine Signalling

The most common example of paracrine signals is the signal transmission through the synaptic gap. Neurotransmitters are the paracrine signaling molecules involved here in transmitting nerve impulses from the pre-synaptic neuron to the post-synaptic neuron.

Similarities Between Juxtacrine and Paracrine Signalling

• Juxtacrine and paracrine signaling are two methods of cell signaling.
• They are important for the development, tissue repair, Immunity, and homeostasis in organisms.

Difference Between Juxtacrine and Paracrine Signalling

Definition

Juxtacrine signaling refers to a type of cell–cell or cell–extracellular matrix signaling in multicellular organisms and requires close contact, while paracrine signaling refers to a form of cell signaling, a type of cellular communication in which a cell produces a signal to induce changes in nearby cells.

Signaling Molecules

Juxtacrine signaling uses ligands and receptors as signaling molecules, while paracrine signaling uses neurotransmitters and hormones as signaling molecules.  

Target

The target of the juxtacrine signaling is in close contact, while the target of the paracrine signaling is in close proximity.

Examples

Membrane contact of two bacteria is an example of juxtacrine signaling while signal transmission through the synaptic gap is an example of paracrine signaling.

Conclusion

In brief, juxtacrine and paracrine signaling are two types of cell signaling methods occurring in cells. Juxtacrine signaling occurs when the cell-to-cell or cell-to-extracellular matrix is in close contact. Also, it occurs through ligand-to-receptor binding. Membrane contact with bacteria is an example of juxtacrine signaling. In comparison, paracrine signaling is a type of cell signaling involving the signaling molecules such as neurotransmitters and hormones. These molecules target nearby cells in paracrine signaling. Also, the signal transduction across the synaptic gap is an example of paracrine signaling. Therefore, the main difference between juxtacrine and paracrine signaling is the type of signaling.  

References:

1. Juxtacrine signalling. Juxtacrine Signalling – an overview | ScienceDirect Topics. (n.d.). 
2. Paracrine signaling. Paracrine Signaling – an overview | ScienceDirect Topics. (n.d.). 

Image Courtesy:

1. “Notchccr” By Fred the Oyster – Own work (Public Domain) via Commons Wikimedia
2. “Signal transduction pathways” By en:User:Roadnottaken – Own Work (Public Domain) via Commons Wikimedia