Name: cell signals that travel between cells
Uploaded: 2023-04-30T11:38:59.000Z
Duration: 1 min 32 s
Channel: JoVE

Cells use signaling molecules or ligands for communication. The molecules that serve as cellular signals vary in their chemical and physical properties, as well as their range of action.
Chemically, ligands may be ions like calcium, small molecules like the neurotransmitter acetylcholine, or peptides and proteins like growth factors.
Dissolved gases like nitric oxide also serve as signals. Additionally, cells respond to physical signals such as light, touch, and heat.
Receptor-ligand interactions are central to cellular signaling. Hydrophilic molecules cannot cross the plasma membrane. Many bind to receptors on the cell surface; however, small hydrophilic molecules may be transported across the plasma membrane to an adjacent cell via gap junctions.
Hydrophobic molecules, like steroid hormones, can freely diffuse through the cell membrane and bind to intracellular receptors.
Signaling molecules can act over long- or short- ranges. Some ligands, such as cytokines, are released by exocytosis into the extracellular space and target distant cells. Whereas membrane-bound ligands, such as integrins, directly bind to receptors on the adjacent cells or to the extracellular matrix.

types of signaling molecules

Types of Signaling Molecules

In multicellular organisms, many molecules transmit signals between cells to pass information. These signals vary in complexity and include small peptides, nucleotides, steroids, fatty acid derivatives, and dissolved gases such as nitric oxide. Some signaling molecules diffuse through the plasma membrane to act locally between neighboring cells or travel long distances. Others remain attached to the cell surface, transmitting information to other cells only when they make contact. In some instances, special processing, such as proteolytic cleavage, may be required to release the extracellular domains of transmembrane signaling proteins. For example, peptide and protein signals are synthesized as inactive pre-pro-peptides in the rough endoplasmic reticulum, converted to pro-peptides by enzymatic cleavage, and further processed in the Golgi apparatus before being enzymatically activated in the transport vesicles destined for exocytosis.
Water-soluble or hydrophilic signals that cannot pass through the non-polar region of the plasma membrane or molecules that are too large to pass through the membrane bind the extracellular domain of cell-surface receptors. The group of molecules that bind the cell surface receptor is diverse. They primarily consist of amino acids that may be unmodified, modified into a derivative, or incorporated into peptides and proteins. For example, neurotransmitters like glutamate and GABA are amino acid signals synthesized and stored in vesicles by the neurons and released by exocytosis. Another neurotransmitter, dopamine, is derived from tyrosine.&#160;
Ions, particularly calcium, control critical cellular processes like muscle contraction, gene transcription, and apoptosis. They may either be involved in direct intracellular communication through gap junctions or may function as second messengers in intracellular signaling pathways. Nitric oxide, a gaseous signaling molecule known for its role in smooth muscle relaxation, diffuses directly across the plasma membrane. The drug nitroglycerin, which is used to treat heart disease, causes the release of nitric oxide. This causes blood vessels to dilate and restores blood flow to the heart.

In multicellular organisms, many molecules transmit signals between cells to pass information. These signals vary in complexity and include small ...

Education

JoVE Core

Cell Biology

Unit 1

Principles of Cell Signaling

KEY TERMS AND CONCEPTS

cell signals that travel between cells

Cell signals that travel between cells carry information in multicellular organisms. These signaling molecules can be small peptides, nucleotides, steroids, fatty acid derivatives, or dissolved gases such as nitric oxide. Some signals act near the cell that released them, while others move over long distances. Other signals stay on the cell surface and work only when cells make contact.

Some signaling proteins need extra processing before they can act. Peptide and protein signals are made as inactive pre-pro-peptides in the rough endoplasmic reticulum. They are then cut into pro-peptides and further processed in the Golgi apparatus. After that, enzymes activate them in transport vesicles before exocytosis releases them.

Water-soluble, or hydrophilic, signals cannot cross the non-polar part of the plasma membrane. Large molecules also cannot pass through this barrier. These signals bind to receptors on the outside of the cell membrane. The molecules that use cell-surface receptors include many amino acid-based signals. Some are unmodified amino acids, some are modified derivatives, and some are part of peptides and proteins.

Neurotransmitters provide clear examples of these signaling molecules. Glutamate and GABA are amino acid signals that neurons synthesize, store in vesicles, and release by exocytosis. Dopamine is another neurotransmitter, and it comes from tyrosine. Ions also help control cell activity. Calcium is especially important for muscle contraction, gene transcription, and apoptosis. Ions may move through gap junctions or act as second messengers in signaling pathways.

Nitric oxide is a gaseous signaling molecule that can diffuse directly across the plasma membrane. It is known for helping smooth muscle relax. Nitroglycerin, a drug used to treat heart disease, causes nitric oxide to be released. This makes blood vessels dilate and helps restore blood flow to the heart.

Cell Signals That Travel Between Cells

overview of cell signaling

Cell Signaling Pathways and Responses

Cell signaling pathways help cells detect changes and respond to their environment. Cells also use signaling to communicate with other cells. Both unicellular and multicellular organisms rely on these signaling systems to share information. Cells often receive messages through receptor proteins on the cell membrane. Skin cells can respond to touch, and photoreceptors in the retina can detect light. Most cells respond to chemical signals such as hormones and neurotransmitters, and the same...

Cell signals that travel between cells carry information in multicellular organisms. These signaling molecules can be small peptides, nucleotides, steroids, fatty acid derivatives, or dissolved gases such as nitric oxide. Some signals act near the cell that released them, while others move over long distances. Other signals stay on the cell surface and work only when cells make contact. Some signaling proteins need extra processing before they can act. Peptide and protein signals are made as...

types of receptors: cell surface receptors

types-of-receptors-cell-surface-receptors

Cell Surface Receptors and Signal Relay

Cell-surface receptors help cells detect signals outside the cell and relay them inward. They are also called transmembrane receptors because they sit in the cell membrane and span the plasma membrane. A ligand is the molecule that binds to the receptor, and it does not need to enter the cell to trigger a response. These receptors are membrane-anchored, integral proteins. They have three main parts. The extracellular domain binds the ligand outside the cell, the transmembrane domain passes...

types of receptors: internal receptors

Steroid Hormone Signaling with Intracellular Receptors

Steroid hormones and other small signaling molecules can enter the cell and bind intracellular receptors. These receptors are found in the cytoplasm or the nucleus. Because the ligands are hydrophobic, they can cross the plasma membrane, unlike many hydrophilic signals. When a ligand binds an intracellular receptor, the receptor changes shape and becomes active. The active receptor can work like a transcription factor. It binds to specific DNA sites and can increase or decrease the...

assembly of signaling complexes

Protein Docking in Cell Signaling

Protein docking helps cells build signaling complexes that pass messages inside the cell. These multiprotein complexes form through protein-protein interactions at the cytoplasmic side of transmembrane receptors. They can also include enzymatic and non-enzymatic proteins linked to the receptor. Together, they help activate and spread intracellular signals that control cell functions. Cell signaling often depends on interaction domains, which are protein parts that recognize specific binding...

interactions between signaling pathways

Cross-Talk in Cell Signaling Pathways

Cell signaling pathways often cross-talk with one another. This means one pathway can influence another instead of acting alone. Cells use these linked pathways to combine signals from the environment and respond in a controlled way. One common pattern is convergence. In convergence, two separate signaling pathways meet at the same functional unit. That unit may be a single protein or a protein complex. The final response can be different from, or stronger than, the response from either...

amplifying signals via second messengers

Cell-Surface Receptors and Second Messengers

Cell-surface receptors use second messengers to carry signals into the cell. Many receptor-binding ligands are hydrophilic, so they do not cross the cell membrane. Instead, they bind to receptors on the outside of the cell and pass the message to the cytoplasm. G protein-coupled receptors can activate the phosphoinositol pathway and the cAMP pathway. In the phosphoinositol pathway, the receptor activates phospholipase C. This enzyme splits phosphatidylinositol biphosphate, or PIP2, into two...

amplifying signals via enzymatic cascade

Turning Off Amplified Cell Signals

Cell signaling depends on both signal amplification and signal shutoff. When a ligand binds to a cell-surface receptor, the receptor changes shape inside the cell. That change can activate an enzyme function or let the receptor bind other molecules. In many signal transduction pathways, one ligand can trigger many downstream targets, so the signal is amplified. Proteins that pass the signal are often phosphorylated, which means a phosphate group is added at one or more sites. This modification...

diversity in cell signaling responses

Cell Signaling Response Speed and Patterns

Cell signaling responses can differ in both pattern and speed. A cell’s function and communication depend on outside signals, internal signaling pathways, and the response that follows. Different cell types do not use the same set of signaling parts. Receptors are selective for their matching ligands, but once activated, they can affect DNA transcription, protein synthesis, and metabolism. Some signaling systems produce graded responses. In a graded response, the cell output changes in...

cell signaling feedback loops

How Cells Balance Signal Strength

Cell signaling is controlled by feedback loops that connect a cell’s output back to its input. Positive feedback and negative feedback help keep signaling systems working in the right range. These loops are especially important when cells need to respond quickly and then adjust that response. Negative feedback loops act as output limiters in many signaling systems. After an input signal starts a response, the response rises quickly until it reaches a threshold. Beyond that point, the negative...

cell signaling in plants

Plant Receptor Kinases and Growth Signals

Plant receptor kinases help cells communicate and control growth, flowering, fruiting, and activity in roots, shoots, and leaves. These signals also help plants respond to changing environmental conditions. Plant signaling works differently from animal signaling, so the receptors used in plants are not the same as those commonly found in animals. Plants mainly use enzyme-linked receptors. In animals, the largest class of cell-surface receptors is the G-protein coupled receptor, or GPCR.

plant hormones

Plant Hormones and Growth Signals

Plant hormones are chemical signals that help control growth and development in plants. They allow different parts of a plant to communicate and respond to changes in the environment. The main plant hormones include auxin, gibberellins, cytokinins, abscisic acid, and ethylene. Each one has a different role, but they often work together to shape how a plant grows, matures, and reacts to stress. Auxin helps direct plant growth, while gibberellins support stem elongation and seed germination.

key terms and concepts

Explore how signaling molecules move between cells, from neurotransmitters and ions to nitric oxide, and how they bind receptors or diffuse through membranes.

Cell Signals That Travel Between Cells | JoVE K12

cell biology

JoVE Core Cell Biology illustrates complex cellular processes in easy-to-understand yet comprehensive animated video lessons. This collection focuses on the essential components and functions of cells, including organelles and membranes, cellular transport, and cell energetics. It is complemented by scientist-in-action videos that demonstrate the application of cell biology in real-world research experiments.

Cell Signals That Travel Between Cells

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