L9 Cell Signalling 1 Flashcards
Types of cell-to-cell signalling
- Endocrine (long range, blood borne hormones)
- Paracrine (short range, localised action growth factors and cytokines)
- Autocrine (same cell, growth factors and cytokines)
Types of extracellular mediators
- Hormones (endocrine action, blood borne, short metabolic effects)
- GFs (paracrine/autocrine, long term proliferation/developmental effects)
- Steroid hormone (intracellular receptors/autocrine, long term)
GPCRs
G-Protein Coupled Receptors: Short term changes in cell function - metabolism, movement
Receptors with serine activity
TGF-beta receptors which phosphorylate and activate Smad transcription factors
Receptors linked to tyrosine kinases
Cytokine receptors (Interleukin-3 receptor)
Receptor Associated kinases
Long term changes in gene expression or development
Ion channel receptors
TRP (transient receptor potential) channels (cation)
Second messenger definition
Intracellular metabolite or ion which couples an extracellular stimulus to a physiological response
Criteria for a 2nd messenger:
- small molecule
- able to induce rapid conc. changes
- controlled by extracellular stimuli
- regulates enzyme activity/protein function
- involves highly specific interactions
- amplification present in system
3’,5’-cyclic AMP
Activates protein kinase A
Upregulates lipid breakdown; downregulates glycogen synthesis
3’,5’-cyclic GMP
Activates protein kinase G
Opens cation channels in rod cells
1,2-diacylglycerol
Activates protein kinase C
Downregulates glycogen synthesis, upregulates transcription
Inositol 1,4,5-triphosphate (IP3)
Opens calcium channels in the endoplasmic reticulum (important second messengers)
Activates calcium-dependent protein kinases
Target of cyclic nucleotides
cAMP-dependent protein kinases
Target of calcium and calmodulin
Calcium-calmodulin protein kinase
