Cell signalling

Question 1

Different methods of cell signalling

Answer 1

paracrine
autocrine
endocrine
cell to cell contact

Question 2

Explain each method of cell signalling

Answer 2

Paracrine- cell releases ligands that attach to another cell nearby

Endocrine- cell releases ligands that travel a long distance throught the blood stream to attach to other cells

autocrine-cell releases ligands that bind to receptor on its self

cell to cell: direct transmition through either gap junctions or complimentary receptor and protein on each others surface

Question 3

general mechanism of cell signalling

Answer 3

reception - ligand binds to receptor
transduction - use of relay molecules inside cell
response- cam be metabolic / affeft transcription etc
feedback loop - response might cause a feedback loop

Question 4

Explain structure of G coupled protein receptor

Answer 4

It is a transmembrane protein with 7 transmembrane domains.
it has a ligand bindin extracellular site
a intracellular g-protein binding site
and a couple phosphorylation sites

Question 5

structure of g protein

Answer 5

g protein is made up of 3 sub units a alpha,beta and gamma subunites
a gdp is attachted to the alpha subunit

Question 6

explain how the gpcr effects g protein ? aka mechanism

Answer 6

once a ligand binds to receptor it

Question 7

What is receptor tyrosine kinases
explain its structure and effects.

Answer 7

Single pass,trans-membrane receptor

it has very different extracellular proteins for each type of tyrosine kinase receptor
intraceullular structure is similar across all and contains a tyrosine kinase domain

controls cell proliferation,differnetiaition,survival,migration etc

Question 8

explain mechanism of RTK

Answer 8

Ligand binding causes dimerization
this leads to intracellular tyrosine kinase domains to activate and phosphorylate each other
phosphorylation of tyrosine allows for docking sites to appear on the cytoplasmic tyrosine kinase domain and once proteins bind it causes a down stream reaction

Question 9

explain GTPases activation by RTKs; Ras

Answer 9

Grb-2 adaptor protein binds to docking site on tyrosine kinase domain,
this recruites ras GEF which reaches close to the gtpases ras protein
this promotes the dissassociation of gdp and the binding of gtp to activate the protein
the now active protein causes a reaction and phosphorylates map-kinase-kinase-kinase which then phosphorylates map kinase-kinase
which phosphorylates map-kinase which then affects effector proteins and cause response