Proteins Flashcards
The liver produces how many types of proteins?
What are these proteins?
3
Plasma proteins, clotting factors, compliment factors
What plasma protein is most abundant?
Albumin
What are the functions of albumin?
Oncotic pressure maintenance (plasma protein) - 66kDa
Carrier protein for unconjugated bilirubin & of other large hydrophobic compounds
Such as, fatty acids, hormones and drugs (NSAIDs & warfarin)
When there is liver failure, what happens to albumin and what does this cause?
Reduction in albumin resulting in less albumin in the blood (hypoalbuminaemia)
Decrease in capillary oncotic pressure resulting in accumulation of water in interstitial fluid leading to oedema
Hypoalbumimaemia=oedema
The liver produces which clotting factors?
Which clotting factors doesn’t it produce?
What does the liver also produce and why is it important for clotting factors?
Produces all CF except Von Willebrand factor (8) and calcium (IV)
Produces bile salts necessary for vitamin K absorption
Vit K is important for synthesis of clotting factors 10, 9, 7, 2
What is the function of complement factors?
Mark pathogens (immune response) To be recognized by phagocytes & neutrophils, then destroyed
Are proteins stored?
Why?
Rarely/never stored, always have a function
Constituent of functional muscle mass
AA have roles in body
What is excess protein stored as?
Fat (excess AA are excreted)
What does protein turnover refer to?
The continuous degradation and resynthesis of all cellular proteins
When is the rate of protein turnover increased?
Tissue is damaged due to trauma
Uterine tissue during pregnancy in skeletal muscle during starvation- gluconeogenesis
Severe burns
What are the 2 ways faulty (damaged) proteins are degredated (brokendown)?
Ubiquitin
Lysosomal
What is the ubiquitin pathway?
Where does it occur?
What happens?
In cell cytoplasm
Small protein, ubiquitin, selectively binds to defective protein
Signals to proteases that protein needs breakdown
(This peptide directs the protein to a protein complex called a proteasome, which unfolds the protein and breaks in down to small peptides)
Lysosomal pathway
What Happens?
Where does it occur?
In reticuloendothelial system (liver) - mediated by kupffer cells
Sinudoidal endothelial cells removes soluble proteins from blood
Protein fused into lysosomes (contain hydrolytic enzymes)
Phagocytosed by kupffer cells (resident macrophage)
Protein>how many polypeptide bonds
Polypeptide < ?
Dipeptide =
> 50
<50
1 bond
What are the functions of globulins?
Antibody functions (most are gamma globulins which are not made in liver but some are alpha/beta globulins which are)
