The key difference between intracellular and intercellular signaling is that intracellular signaling is the communication within the cell while intercellular signaling is the communication between cells.
Cells release signaling molecules to target cells and communicate with each other via signaling molecules in multicellular organisms. Target cells have receptors on their cell surfaces and in the cytoplasm to receive signals and act accordingly. Also, within the cell, communication occurs between organelles and nucleus to carry out cellular functions. Therefore, there are two types of cell communication as intracellular signaling or communication and intercellular communication or signaling.
CONTENTS
1. Overview and Key Difference
2. What is Intracellular Signaling
3. What is Intercellular Signaling
4. Similarities Between Intracellular and Intercellular Signaling
5. Side by Side Comparison – Intracellular vs Intercellular Signaling in Tabular Form
6. Summary
What is Intracellular Signaling?
Intracellular signaling refers to cell communication that occurs within the cell. Receptors located on the cell membrane receive a signal and convert into an intracellular signal. Then intracellular receptors continue signal transmission to the target within the cell.
Figure 01: Intracellular Signaling
Intracellular signaling cascade involves many components, and their modifications occur by enzymes. Phosphorylation is the most common chemical modification that takes place during intracellular signaling; it activates enzymes that are essential for the downstream process. Moreover, phosphorylation causes changes in their shapes. In phosphorylation, kinase enzyme catalyzes the addition of phosphate group into molecules. Furthermore, intracellular signaling uses secondary messengers such as calcium ion, diacylglycerol, inositol triphosphate and cyclic AMP, etc.
What is Intercellular Signaling?
Intercellular signaling is the communication that exists between cells. Cells send signals to target cells in the form of chemical signals or signaling molecules. It releases signaling molecules called ligands into the extracellular matrix. These signaling molecules carry the message and diffuse in the extracellular matrix towards the neighboring cell, which is the target cell. To receive the signal, target cells have receptors that are protein molecules. Receptors present on the cell surface bind with the extracellular or external ligand and communicate with the sending cell.
In animal cells, cells communicate with neighboring cells via gap junctions. Nerve cells transmit signals from one neuron to another by neurotransmitters. There is a junction called synapse between two neurons. Neurotransmitters released from the sending neuron (presynaptic neuron) travel across the synapse and reach the receptors of the target neuron (postsynaptic neuron). In this manner, nerve cells communicate with each other and transmit signals throughout the body.
Figure 02: Signal Transmission Between Neurons
Furthermore, the plant cells communicate with neighboring cells via plasmodesmata. Almost all plant cells have plasmodesmata for communication between cells. Therefore, plasmodesmata facilitate a communication network within the plant.
What are the Similarities Between Intracellular and Intercellular Signaling?
- Intracellular and intercellular signaling are two communication methods of cells.
- Signaling molecules and receptors participate in both pathways.
- They are vital for cell functions and overall communication in multicellular organisms, including animals and plants.
- Also, both signalings function according to regulatory mechanisms.
What is the Difference Between Intracellular and Intercellular Signaling?
Intracellular signaling is the communication that takes place within the cell. In contrast, intercellular signaling is the communication that takes place between the cells. So, this is the key difference between intracellular and intercellular signaling. Moreover, intracellular signaling is important for the differentiation and development of an organism and also critical for the processing of sensory information. Meanwhile, intracellular communication controls all functions happening in the cell, including the intermediary metabolism, cell division activity, morphology, and the transcription program. Therefore, this is the functional difference between intracellular and intercellular signaling.
Summary – Intracellular vs Intercellular Signaling
Cell communication can be intracellular signaling or intercellular signaling. Intracellular signaling takes place within the cell. It is the signaling chain happening inside the cell in response to extracellular and intracellular stimuli. In contrast, intercellular signaling takes place between cells. Communication between cells has great importance in the differentiation and development of an organism and is also critical for the processing of sensory information. Meanwhile, intracellular communication controls all functions happening in the cell, including the intermediary metabolism, cell division activity, morphology and the transcription program. Thus, this summarizes the difference between intracellular and intercellular signaling.
Reference:
1.”Signaling Molecules and Cellular Receptors.” Boundless Biology. Lumen, Available here.
Image Courtesy:
1. “CREB cAMP neuron pathway” By Evrae8 – Own work (CC BY-SA 4.0) via Commons Wikimedia
2. “Reuptake both” By Sabar – self-made, created with Corel Painter and Adobe Photoshop (Public Domain) via Commons Wikimedia