Lecture 6- Biochemistry of signaling pathways Flashcards
minus gap junction signaling, what does cell to cell signaling require? (3)
signal (ligand)
receptor
way to get the message across (intracellular signaling pathways)
what is a signal transduction pathway?
information from secreted signals is converted to intracellular signal pathways, therefore, converts one form of signal to another
explain signal transduction (5)
signal molecule –> binds to receptor protein –> activates intracellular signal molecules –> causes alterations of target proteins –> creates a biological response
are signal pathways ubiquitous/ everywhere?
all cells have some pathways and only certain cells have specific pathways
why are signal pathways important?
they amplify signals to cause a large biological effect
what are the two main categories based on receptor location?
intracellular receptors
cell membrane receptors
what state are ligands in with intracellular receptors?
lipophilic (hydrophobic), therefore fat soluble
with intracellular receptors can ligands diffuse through cell membrane? what do they bind to?
yes, then they bind to receptors in the nucleus or cytosol
what do intracellular receptors alter?
gene expression (happens slowly but its long lasting)
with intracellular signal receptors is the response fast?
no, theyre slower responses that are related to changes in gene activity
what state are ligands in with cell membrane receptors?
lipophobic (hydrophilic) water soluble
with cell membrane receptors can ligands diffuse through cell membrane? what do they bind to?
no, they bind to membrane receptors which cause intracellular cascade
with cell membrane receptors is the response fast?
yes
what are the 4 cell membrane receptors?
integrin receptor
receptor channel
receptor- enzyme
G protein- coupled receptor
what does the integrin receptor do?
binds extracellular matrix proteins
binding of the ligand with integrin receptor stimulates what change?
changes in the cytoskeleton
what can changes in the cytoskeleton affect?
cell movement
growth
wound healing
how do receptor channels work?
ligand binds to the receptor channel protein and a channel gate either opens or closes (allowing ions to ener and leave).
this alters the cells permeability to an ion and membrane potential
how do receptor channels have an electrical effect?
when activated ions cross cell membrane they are charged which causes an electrical signal/ effect
what ligand normally binds to a receptor channel?
neurotransmitter
what ion is always allowed into cells through receptor channels?
Calcium!!! (important for intracellular signal)
recall: Ca++ inside the cell is low
what are receptor channels often called?
ligand- gated ion channels
neurotransmitter gated ion channels
ionotropic receptors
what do receptor enzymes and GPCR have in common?
activate amplifier enzymes
how does signal amplification work?
receptor- ligand complex activates an amplifier enzyme
1 ligand is amplified into many intracellular molecules
what is the takeaway message about the ligand from signal amplification?
a small amount of ligand creates a large effect
what is an example of a receptor enzyme pathway?
tyrosine kinase receptor
what is the general goal of tyrosine kinase receptors?
to transfer a phosphate group from ATP to a tyrosine residue (amino acid) of a protein which phosphorylates tyrosine residues