Signaling text book summary: Difference between revisions
Jump to navigation
Jump to search
No edit summary |
No edit summary |
||
Line 63: | Line 63: | ||
N.B. This means that a simple hormonal trigger can produce a very complex pattern of gene expression. | N.B. This means that a simple hormonal trigger can produce a very complex pattern of gene expression. | ||
==Cell surfacce receptor proteins== | |||
3 kinds: | |||
===Ion-channel linked cell surfacce receptor proteins=== | |||
N.B. these are the transmitter-gated ion channels that were updated in the transport overhaul. The top level term is already in place. | |||
p842 | |||
===G-Protein linked cell surface receptor proteins=== | |||
===Enzyme linked cell surfacce receptor proteins=== | |||
Revision as of 11:46, 25 March 2008
From Molecular Biology of the Cell - Cell Communication Chapter
Contact-dependent signaling
development and immune system p833
local mediators (paracrine signaling)
p834
- signals don't travel far
- soon taken up
- rapidly destroyed
- immobilised
long distance signals - nervous system
p834
- nerve cell - electric impulses (action potentials) fast (up to 100m/s)
- neurotransmitters
- chemical synapses
see chapter 11 for synaptic signaling processes.
Long distance signals - hormones for endocrine cells
- transported via the bloodstream
- slow acting
low concentration -> large effects.
Autocrine signaling
- Cell secretes a signal that can bind back to its own receptors or those of the same cell type.
- For example in development this is used to maintain cell identity after initial differentiation.
- Also used to make sure all adjacent cells differentiate in the same way.
Gap junctions
- Allows cell to communicate with each other by having a tunnel across the plasma membrane
- Dye can squirt through the tunnels and this is how people spot them experimentally.
- Patterns of making and breaking gap junctions are important in development.
Nitrous Oxide
- NO and CO and other similar small hydrophobic molecules are able to pass straight through the membrane and are used as signals.
- These bind to intracellular receptor proteins.
- e.g. steroid hormones, thyroid hormones, retinoids, vitamin D.
- The signal molecules bind to the receptor molecules, which then become activated, and are able to bind to DNA to regulate transcription.
- The receptors are all members of the nuclear receptor super family.
- This leads to the primary and secondary response:
Signaling to control gene expression - Primary response
- ligands bound by hormones bing to gene regulatory bits and turn on expression.
- This takes about 30 minutes
Signaling to control gene expression - Secondary response
- Protein products made in the primary response activate other genes to produce a delayed secondary response.
N.B. This means that a simple hormonal trigger can produce a very complex pattern of gene expression.
Cell surfacce receptor proteins
3 kinds:
Ion-channel linked cell surfacce receptor proteins
N.B. these are the transmitter-gated ion channels that were updated in the transport overhaul. The top level term is already in place. p842
G-Protein linked cell surface receptor proteins
Enzyme linked cell surfacce receptor proteins
Some general features in signaling
- Cells are bathed in hundreds of different singals all the time.
- response of different cells to the same signal can be depend on the internal machinery, even if the receptor is the same.
- some effects on cell are premenant due to cell memory - though this is usually not the case. (chap 7 + 21)
- half life is important as signal concentration cannot change quickly if the signal is not broken down quickly.
- e.g. if phosphorylation is an important part of signaling then there must also be rapid dephosphorylation to keep background signal level low.
- speed of response of a cell also depends on turnover of internal chemical (p837-838).