Signal Transduction and Cell Communication

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Cell Communication

No cell lives in isolation. Cellular communication is a fundamental property of all cells and shapes the development and function of every living organism.

Signaling molecules illicit a specific response only in target cells that have a receptor for that signal! There can be many types of signals like:

Small molecules (acetylcholine)

Peptides

Soluble proteins (Insulin)

The key thing to remember here is that receptors and its signal molecules are best friends . Most receptors bind to a single molecule or closely related molecules.

Signaling molecules can come in different sizes and characteristics:

Small and hydrophobic

Large and Hydrophilic

Not all molecules can diffuse into intracellular receptors. This is especially true for Large and hydrophilic signaling molecules. These molecules have to bind to cell surface receptors in order to get inside of the cell.

Cell surface receptors are integral membrane proteins or trans-membrane proteins! They also possess three important domains:

Cystoplasmic

Exoplasmic

Membrane-spanning

Signal Transduction!

What exactly is it? Converting an extracellular

signal to an intracellular response.

Look over to the right for animations directly pertaining to this concept.

https://youtu.be/FtVb7r8aHco (Incorporar)

https://youtu.be/qOVkedxDqQo (Incorporar)

Cells Can Communicate from Different Distances

Endocrine Signaling- Can interact with distant targeting cells via the circulatory system. Also involves hormones when they act as signaling molecules that can facilitate endocrine signaling.

Paracrine Signaling- These are signaling molecules released by the cell that interact with target cells in close proximity. For example: neurotransmitters and growth ffacts that regulate our development.

Autocrine Signaling- Cells that will act on themselves.

Some signals can act on both long distances or short distances.

Signals and receptors hold a special relationship with each other. There are different cell types that do different functions. Each of those cell types can have different receptors for the same ligand, or different cell types may have the same receptor. In both scenarios, one kind of receptor can induce a different response depending on the cell type.

Effector specifity refers to the ability to recognize the effector molecule by receptors on effector tissue and allow it to attach to its surface while disallowing similar non effector molecules from attaching it hence the specifity.

Similar to binding specifity which depends on molecular complementary. Like fitting a Lego with its other compatible piece.

Specifity will depend on the receptor:

Acetylcholine binds only acetylcholine

Insulin receptor will bind insulin, but it will

also bind insulin-like growth factors