FOM Week 1 Flashcards
What is the purpose of the cytoskeleton?
Structural strength, transport, movement and directional info
What does it mean when a cytoskeleton is dynamic?
location and life cycle can alter the protein output and ratios
At what end does actin tend to have subunits added to?
The plus end, but can have units added to the minus end
What important molecule does actin have a binding site for?
ATP binds right in the center
What are ARPs? What do they do?
ARPs for a complex and bind to the minus end of the actin filament, stabilizing it. Filament will then grow rapidly on plus end. They also bind other acting molecules at a 70 degree angle and create a meshwork
How do microtubules compare to actin?
They are thicker and consist of heterodimers of alpha and beta tubulin subunits 13 protofilaments come together
What are the locations of the plus and minus end of a microtubule?
Plus end lies in the periphery and the minus end is in the centriole
What is the purpose and outcome of the GTP cap on microtubules?
GTP cap stabilizes microtubule allowing for growth
What happens to a microtubule with a GDP cap?
a GDP cap is unstable, the microtubule will begin to shrink GDP encourages curving of the protofilament which can lead to shrinking
What can be used to stabilize the minus end of a microtubule?
Gamma tubulin
What is formin?
Dimer that allows actin to grow faster by stabilizing the plus end and adding subunits
What is profilin?
binds actin to enhance ATP binding and adds actin subunits to the plus end
What is cofilin?
binds actin and condenses it leading to a shorter and thicker filaments
What is a subunit example of a microfilament?
actin
What are a few subunit examples intermediate filaments?
Vimentin (mesenchyme) Glial fibrillary acidic proteins (glia) Neurofilament (neurons) Keratins (epithelia) Nuclear lamin Desmin (muscle)
What is a subunit example of microtubules?
alpha and beta tubulin
What are the common structural properties of fibrillar proteins?
Repeating globular subunits and long twisting fibers Building structures for cytoskeleton or ECM Actin tubulin - repeating alpha and beta subunits creating protofilaments
What are the common structural properties of integral membrane proteins? What are examples?
Surrounded by hydrophobic lipid membrane Inside out distribution of amino acids - hydrophobic amino acids span the membrane and hydrophilic sit outside the membrane Bundles of alpha helicies and beta barrels
What are the common structural properties of intrinsically disordered proteins?
- Not globular 2. Unpredictable secondary structure 3. No hydrophobic core 4. Long repetitive sequences 5. Appear to fold when binding targets 6. Bind wide range of targets
Explain the characteristics of proteins with similar sequences
These are homologs Can have as little as 25% of same seq but have similar function Difference in residues lead to individual characteristics
What are the functional classes that proteins can share?
Chemical Signaling structure transport storage
Provide an example of an isoform and explain what it is.
Hexokinase (phosphorylates many sugars) vs glucokinase (phosphorylates just glucose) Isoforms have same general function but subtle differences
Can proteins share a common ligand? If so explain.
Yes Many proteins can bind ATP and have similar binding sites for this to occur
What are two common post-translational modifications?
Phosphorylation and proteolysis















