cellular signalling

Question 1

what is intracellular signalling?

Answer 1

its signalling within the cell

Question 2

what is intercellular signalling?

Answer 2

it signalling outwith the cell

Question 3

what types of intercellular signalling are there?

Answer 3

autocrine signalling
endocrine signalling
paracrine signalling
exocrine signalling

Question 4

what is autocrine signalling?

Answer 4

it a cell targeting itself by producing messengers which can bind to the cell
common in the immune system and embryogenesis

Question 5

what is an example of a cell which uses autocrine signalling?

Answer 5

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

Question 6

what is endocrine signalling?

Answer 6

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

Question 7

what is exocrine siganlling?

Answer 7

it is signalling that acts on distinct targets through the ducts

Question 8

what organ uses exocrine and endocrine signalling?

Answer 8

liver

Question 9

what is paracrine signalling?

Answer 9

it when the cell targets a nearby cell

Question 10

what can one signalling molecule lead to?

Answer 10

many different cell responses, this depends on the type of cell receiving the signal

Question 11

what are the major types of cell signal receptors?

Answer 11

G-protein coupled receptors
kinase-linked receptors
nuclear receptors
ligand gated ion channels

Question 12

what are the major types of cell signal receptors?

Answer 12

G-protein coupled receptors
kinase-linked receptors
nuclear receptors
juxtocrine signalling

Question 13

what is GCPR signalling?

Answer 13

its signalling by G-protein coupled receptors (GCPRs)

Question 14

how does GCPR signalling work?

Answer 14

• 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

Question 15

what happens when an extracellular signalling molecule binds to the GCPR?

Answer 15

it causes a conformational change which causes it to interact with a G protein

Question 16

what is an endosome?

Answer 16

its a collection of intracellular sorting organelles

Question 17

what is a signalosome?

Answer 17

its a big supramolecular complex which is made up of unique combinations of signalling pathway components

Question 18

what do signalosomes do?

Answer 18

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

Question 19

what is the role of domains in the cell membrane?

Answer 19

theyre where lipids and receptors are all together to make cell signalling more efficeint

Question 20

what are caveolae?

Answer 20

theyre specialised microdomains which cause the plasma membrane to fold back in on itself

Question 21

what coats the calveolins?

Answer 21

cholesterol and

Question 22

what coats the calveolins?

Answer 22

cholesterol and sphignoids

Question 23

what is the function of caveolae?

Answer 23

they work as platforms to recruit components of signal transduction and act as signalling molecules

Question 24

what do phosphodiesterases (PDE) do?

Answer 24

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

Question 25

what is cAMP?

Answer 25

its a soluble messenger which can diffuse into the cytosol
cells can have lots of cAMP gradients

Question 26

is there PKA activation in cAMP signalling?

Answer 26

no

Question 27

how many PDEs are involved in cAMP signalling?

Answer 27

14 different ones

Question 28

why is there no PKA activation in cAMP signalling?

Answer 28

because the cells are hydrolysed

Question 29

what does ‘compartmentalisation’ mean?

Answer 29

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

Question 30

what is GcP?

Answer 30

its a rare dinucleotide of CG repeats in the genetic code

Question 31

what are GcP islands and what is their role?

Answer 31

theyre regions of the DNA with lots CG repeats and are often found near the promoter region of the gene
they’re promoters

Question 32

what happens when the GcP islands are methylated?

Answer 32

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