The document provides a comprehensive overview of cell signalling, focusing on signal transduction and receptor tyrosine kinases. It covers various types of cellular communication such as contact-dependent, paracrine, synaptic, endocrine, and autocrine signalling. It details the role of receptors a...
Cells To Systems - Cell Signalling
Cell Signalling - Signal Transduction & Receptor Tyrosine Kinases
Cellular Communication:
No cells exist in isolation (each cell needs to know what the neighbouring cells are doing)
Signals are constantly produced
Signals need to be constantly received, processed, interpreted and response has to be generated
Signals are generally transmitted across the environment in the form of soluble/insoluble molecules
These molecules must be detected and appropriate responses must be produced
The biggest barrier to this process is the cell membrane
The membrane is impermeable to large soluble molecules
Some are transported across the membrane
Others are detected outside of the cell through the receptor and a signal has to be transmitted/conveyed into the
cell
Receptors - Receive signalling from the outside of the cell
Contact Dependent:
For a signal to be received, 2 components are needed to start this
1. Signalling molecule
2. Receptor on the cell surface
In The Form Of How This Is Passed Is Different:
Sometimes, both the receptor and the signalling molecule will be transmembrane proteins
Signalling cell will have a molecule which is sitting on the plasma membrane
Receiving cell will have a receptor which will be embedded in the membrane
Both cells have to be in very close contact for the signal to be passed on from 1 cell to another
Paracrine Signalling:
Secreting soluble molecules
They can diffuse
The cells that are in close neighbourhood (if they have the receptors for these ligands/signal molecules) can receive
signals
The closer the responding cells are to a signalling cell, the stronger response they will produce as they receive most
of the signal there. However, this a short distance signalling
Synaptic Signalling:
Specific form of cell signalling
When we think of neurons, they have cell bodies, 1 axon which is going to emit signals and they have other signals
coming in through dendrites
With the target cell, there is a special formation of a synapse
From the axon they have molecules that are secreted and the target cell is going to receive them
Sometimes the signals have to cross a very long distance e.g synaptic nerve to the foot
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, Cells To Systems - Cell Signalling
Endocrine Signalling:
The signalling molecules have to travel through the bloodstream to go to the target cell
Can be a very long distance until they meet their target cell
Autocrine/Self-Signalling:
A very specific type of signalling
The same cell is secreting signals and receiving them
Receptors & Ligands:
For signalling to be initiated, receptors and signalling molecules are needed
If the cell does not express an appropriate receptor for certain types of signalling molecules, then the particular
signal cannot respond
Ligand - A molecule that binds to a receptor e.g. the ligand of the insulin receptor is insulin
Some receptors will be very specific and can only bind to 1 type of signal, but for some receptors, they can bind to
different types of ligands
There will be ligands which will be very specific and can only bind to 1 receptor, or there will be ligands that can
bind to multiple receptors
Different ligands can produce different responses at the same receptor e.g. agonist/antagonist
So-called receptors communicate signals to cells
Thousands of receptors exist in humans
Intracellular
Cell surface (ion channel-, G protein- and enzyme- coupled
Single Transduction - Process where 1 type of signal is converted to another
The Plasma Membrane As Interaction Surface With The Surrounding Of A Cell:
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