cellular signalling Flashcards
what is intracellular signalling?
its signalling within the cell
what is intercellular signalling?
it signalling outwith the cell
what types of intercellular signalling are there?
autocrine signalling
endocrine signalling
paracrine signalling
exocrine signalling
what is autocrine signalling?
it a cell targeting itself by producing messengers which can bind to the cell
common in the immune system and embryogenesis
what is an example of a cell which uses autocrine signalling?
endothelial cell
it produces nitric oxide to bind with nearby cells and produce a response
but nitric oxide is very unstable so it only works with nearby cells
what is endocrine signalling?
its when a cell targets a distinct cell through the blood stream
like hormones
they’re made and work through the bloodstream and its long distance signalling
what is exocrine siganlling?
it is signalling that acts on distinct targets through the ducts
what organ uses exocrine and endocrine signalling?
liver
what is paracrine signalling?
it when the cell targets a nearby cell
what can one signalling molecule lead to?
many different cell responses, this depends on the type of cell receiving the signal
what are the major types of cell signal receptors?
G-protein coupled receptors
kinase-linked receptors
nuclear receptors
ligand gated ion channels
what are the major types of cell signal receptors?
G-protein coupled receptors
kinase-linked receptors
nuclear receptors
juxtocrine signalling
what is GCPR signalling?
its signalling by G-protein coupled receptors (GCPRs)
how does GCPR signalling work?
- its initated by the cell membrane
- then signalosomes and physical barriers help the compartmentalisation of the signalling
- GCPRs can signal from endosomes after the receptor has been internalised then travel to a pre-golgi compartment
- they work like an inbox for messages to tell cells about other cells and the environment
- when an extracellular signalling molecule binds to the GCPR, it causes a conformational change which causes it to interact with the G protein
what happens when an extracellular signalling molecule binds to the GCPR?
it causes a conformational change which causes it to interact with a G protein
what is an endosome?
its a collection of intracellular sorting organelles
what is a signalosome?
its a big supramolecular complex which is made up of unique combinations of signalling pathway components
what do signalosomes do?
the go to separate intracellular localisation via the association of anchor or adaptive proteins
they’re very adaptive and dynamic
they allow cells to make the best subdomain for signalling
what is the role of domains in the cell membrane?
theyre where lipids and receptors are all together to make cell signalling more efficeint
what are caveolae?
theyre specialised microdomains which cause the plasma membrane to fold back in on itself
what coats the calveolins?
cholesterol and
what coats the calveolins?
cholesterol and sphignoids
what is the function of caveolae?
they work as platforms to recruit components of signal transduction and act as signalling molecules
what do phosphodiesterases (PDE) do?
catalyse the breakdown of cAMP
stop the signal if you want to
contribute to the intracellular signalling pathway
limit diffusion of cAMP in the cytosol
regulate cAMP dynamics
what is cAMP?
its a soluble messenger which can diffuse into the cytosol
cells can have lots of cAMP gradients
is there PKA activation in cAMP signalling?
no
how many PDEs are involved in cAMP signalling?
14 different ones
why is there no PKA activation in cAMP signalling?
because the cells are hydrolysed
what does ‘compartmentalisation’ mean?
it means there can be one signal which causes many responses
the same receptor on one cell can cause a different effect on another cell type
all the cells have different intracellular effector proteins
what is GcP?
its a rare dinucleotide of CG repeats in the genetic code
what are GcP islands and what is their role?
theyre regions of the DNA with lots CG repeats and are often found near the promoter region of the gene
they’re promoters
what happens when the GcP islands are methylated?
they can alter gene expression becuase it stops the binding of transcription factors
the methylated GpG island can act as a binding site for methylated proteins, methyl binding proteins can then turn off transcription
