protein folding Flashcards
PDI’s
protein disulfide isomerase
Catalyzes the formation of thermodynamically favorable disulfide bonds within proteins (in proteins that possess more than two cysteine residues), if less energetically favorable disulfide bonds are formed.
Ubiquitin function
A small, regulatory protein added to another protein via ubiquitination. Can mark a protein target for degradation by proteasomes.
ubiquitination
addition of ubiquitin to the ε-amino group of lysine residues of a substrate protein; occurs in three stages
Activation: performed by ubiquitin-activating enzymes (E1s)
Conjugation: performed by ubiquitin-conjugating enzymes (E2s)
Ligation: performed by ubiquitin ligases (E3s)
Degradation of proteins via polyubiquitination
Polyubiquitinated proteins are recognized by proteasomes.
Proteins are broken down into peptides via hydrolysis of peptide bonds.
Autophagy
Autophagosomal membranes fuse and form an autophagosome that sequesters intracellular debris (e.g., proteins, lipids, cell organelles). It later fuses with lysosomes in order to degrade the macromolecules.
***Can also trigger innate immunity by taking a piece of the pathogen to the right place
What condition is cause by decreased degradation of CFTR protein which is responsible for transport of Cl- across the membrane?
Cystic fibrosis
Causes of amyloidosis
limited proteolysis of abnormal proteins or abnormal folding of abnormal protein–> aggregates amyloid proteins–> disease
What are the 3 major classes of plasma proteins?
Albumins, globulins, and fibrinogen
What are the major functions of plasma proteins?
Plasma proteins include enzyme inhibitors and transport proteins for nutrients, ions, metals, hormones, and many drugs
What unique properties does Albumin have? What is its unique role?
Albumin’s primary role is protecting plasma volume and cardiac pump function.
Albumins (like other plasma proteins) are large and cannot escape from blood. Because of this, it creates large osmotic pressure that draws water into the blood.
What is a prion?
A misfolded protein that has an increase in beta-sheet structure and induces a conformational change of normal cellular prion proteins (PrPc). Intracerebral accumulation of prions leads to plaque formation that causes neural cell death and progression to spongiform encephalopathy.
What are the four processes that feed cargo to lysosomes?
Functions of Ubiquitin
- degradation of proteins by proteasome
- Cellular localization of proteins (protein trafficking)
- Activation or inactivation
- Regulation of protein-protein interactions (cell cycle, translation, and DNA repair)
MOSTLY—polyubiquitinates ineffective structures for destruction in proteasome
What properties define each type of protein folding?
primary: peptide
secondary: hydrogen bonds
Tertiary: disulfide, hydrophobic
Quaternary: salt bridges, multiple peptides
Albumin
where is it?
What is its most important function?
It is a plasm protein in the blood and helps to draw water into blood to protect plasma volume and protect cardiac function
