Signal transduction W4 Flashcards
three common elements of signal transduction pathways
receptor
intermediate
target
signal transduction is the process by which a cell…..
converts one kind of signal into another sequence of rapid biochemical reactions
components of signalling pathways (5)
first messengers/signals/ligand
receptor
second messengers/intermediates
target
response
what is a lignad
something that binds to another molecule
what are first messengers/ signal / lignd
extracellular factors eg hormones neurotransmitters
what do receptors do
receive initial signal from messenger/signal/ligand
what does the second messenger/intermediate do?
amplifies the signal from receptor to target
what does the target do
interacts with intermediate to initiate response
a cell receives a signal what are the four common outcomes of this
can lead to activation or inhibition of
- protein synthesis/gene expression
- enzyme activity
- membrane channels
- cellular processes (eg cell division, metabolism, transport)
where can receptors be found
they can be membrane bound or internal
how does the ligand enter the cell
via diffusion
explain how signalling is specific
only cells with specific receptor will respond to a corresponding signal
describe the differnece between outocrine and paracrine signalling
autocrine signaling means that the initial signal/messenger/lignad is produced by the same cell that receives it
paracrine signalling occurs when the initial messenger/signal/ligand is received by a different cell from which it was produced (you have a signalling cell and a target cell)
explain long distance signalling (endocrine)
occurs when for eg hormones travels through body via bloodstream to target celss
what is the primary requirement for all signalling
that it is easily reversible
Three major classes of extracellular receptors
ligand gated ion channels
enzyme-coupled receptors
G-protein-coupled receptors
cascading chain of reactions - how is kinase and phosphatase involved
kinase - activates proteins by adding a Pi
phosphotase inactivated proteins by removing a Pi
explain phosphorylation cascade
phosphate attaches to protein = activates
releases phosphate= deactivates, phosphate travels to next protein and chain continues
G- protein coupled receptors (GPCRs) have …..transmembrane domains
7
what are G proteins associated with
GPCRs
what is the structure of a G protein
it is heterotrimeric with three subunits (alpha beta gamma)
what does the alpha subunit of a g protein do
exchanges GDP for GTP
what does the alpha subunit containing GTP do
it goes to adenylate cyclase (AC) which generates a second messenger from ATP—cylcic AMP (cAMP)
dysregulation in signal transduction contributes to diseases such as …(4)
cancer, endocrine, autoimmune and neurological disorders
