Lecture 4 - Protein Structure Flashcards
What does GFP do?
Green fluorescent protein (GFP) transmits fluorescence in the green range when you shine blue light on it.
What is kinesin?
Kinesin is a molecular motor protein that interacts with microtubules to transport cellular components (like vesicle).
What does the primary structure of a protein refer to?
The primary structure refers to the composition of amino acids as they appear in a linear fashion forming a chain.
What are the three main secondary structures?
Alpha-Helix, Beta-Sheet, and Beta-Turn
What are alpha-helices? What do they consist of?
Alpha helices are rigid helical structures in proteins. They form by the interaction of the carbonyl oxygens with their respective amide hydrogen about 4 residue away.
What are beta-sheets? What do they consist of?
Beta-sheets are flat sheets made out of a polypeptide chain. They form when amino acids interact to form a lateral strand. Hydrogen bonding between carbonyl oxygens and amide hydrogens stabilize the chain in a horizontal way.
What two forms of beta-sheets exist? What is the difference?
Parallel and Anti-Parallel
In parallel, the N-terminus is always at the same end. In anti-parallel, the terminus alternates which end it is at.
What beta-sheet structure exists in GFP?
Beta-Barrel
What are beta turns? What do they consist of?
Beta turns are secondary structures that confer a rapid turn in the amino acid. They consist of 4 amino acids with hydrogen bonding (carbonyl oxygen to amide hydrogen) between the 1st and 4th residue.
Which two amino acids are often found in beta-turns? Why?
Glycene is often found in beta-turns because they don’t have a bulky R-group and prolene is often found in beta-turns because it introduces a kink into the chain.
What type of interaction are tertiary structures dependent on?
Hydrophobic Interactions
What are globular domains?
Globular domains are tertiary structures that are usually well folded and highly soluble proteins.
What are fibrous domains? What are they important for?
Fibrous domains are tertiary structures that are usually large, rigid, and often quite insoluble. They are useful for structural functions within the cell.
What are intrinsically disordered proteins?
IDPs are newly discovered domains which are completely unstructured. They are very complicated and they never fold into one particular structure. They tend to have much more charge, are less hydrophobic, and flip through various conformations.
What can IDPs trigger? Why is this important?
IDPs can trigger a de-mixing (also known as phase separation) of various proteins and components within the cell which is critical for transcriptional activation, dealing with various types of cellular functions, or forming an environment for proteins that would normally never see each other to come together.
