Sigaling basics Flashcards
What organism is on the brink of single and multi cellularity? (can change depending on survival condition)
Dictosteylium (is an amoeba)
when starved cells aggregate to form a multicellular body.
cells making up the stack will die to give way to the fruiting body (spores)
Prenylated proteins, dually acetylated proteins and GPI anchored proteins can all be found where in the membrane of a cell?
Lipid rafts
What type of phospholipids would you find in a lipid raft?
saturated fatty acids allow tighter packing
How do lipid rafts form?
spontaneously, natural result of segregation of different lipid components in the membrane.
What are gap junctions?
Created by connexin proteins, junctions between adjacent where small signals eg cAMP and Ca can pass through
What is endocrine signaling?
Long distance signaling (eg hormones in blood stream/transpiration)
What is paracrine signaling?
Target nearby cells eg growth factors and neurotransmitters
What is autocrine signaling?
cells make their own signal and react to it themselves
What are some ways to increase switch like behaviour of a ligand/receptor complex?
Cooperativity - if more than one ligand/ binding event has to occur for signal to be transduced, the signal will be more switch like (eg haemoglobin)
Is it good for a receptor to be sensitive?
NO - binding and activation are random at the olecular level. So increased sensitivity = increased random activation.
What is the optimal Kd for a ligand?
Roughly physiological concentration - this means only a slight increase will have switch on etc. easy to control in the body
What is the maximum possible kon (ie physical limit impose by diffusion?)
10^8m-1s-1
what is affected by tight binding and kon that makes it problematic to have a low Kd?
Half life is too long if you have very tight binding
What is the formula of half life for a first order reaction?
ln2/koff
What are arrestins?
Proteins that bind phosphorylated receptor to block the signal transduction even when the ligand is still bound.
