Protein 1 Flashcards
What are the 5 conditionally indispensable amino acids
Tyrosine Cysteine Proline Arginine Glutamine
What are the substrate(s) for tyrosine
Phenylalanine
What are the substrate(s) for cysteine
Methionine, serine
What are the substrate(s) for proline
Glutamate
What are the substrate(s) for arginine
Glutamine or glutamate, aspartate
What are the substrate(s) for glutamine
Glutamate, ammonia
What is primary structure
linear sequence of amino acids in the polypeptide chain
Secondary structure
formed through hydrogen bonds between backbone atoms
Tertiary structure
Describes the overall 3-D arrangement of amino acids within a protein
What is an important characteristic of tertiary structure
Determines the function of protein
Quaternary structure
3-D arrangement of multiple polypeptide chains
3 Examples of proteins with quaternary structure
Hemoglobin
Insulin receptor
Myosin
What are the two pathways for protein degradation
Autophagy-lysosomal
Ubiquitin-proteasome degradation
3 Characteristics of autophagy-lysosomal
- Present in cytoplasm of cells
- Less selective in targeting specific proteins for degradation
- Degradation of whole cell organelles
2 Characteristics of ubiquitin-proteasome degradation
- Present in nucleus and cytoplasm of cells
* Degradation of short-lived proteins
7 steps of ubiquitin-proteasome pathway
- Ubiquitin is activated by enzyme E1
- Activated ubiquitin is transferred from E1 to E2
- Ubiquitin is ligated to protein to be degraded (protein substrate) by E3
- Additional ubiquitin molecules are attached (usually 4 more for a total of 5 ubiquitins)
- Protein substrate is unfolded (ATP is required)
- Ubiquitin molecules are released for re-use as well as free amino acids
- Pro teases in the 26s proteasome breaks down protein substrate
26S proteasome
Large multi subunit complex used in ubiquitin-proteasome pathway
How do proteins enter the autophagy-lysosomal pathway
via endocytosis
What are lysosomes
Cell organelles
Where are lysosomes not found?
Where are they more abundant?
RBC
Liver cells
What types of enzymes do lysosomes contain
endopeptidases and exopeptidases
cathepsins
What are cathepsins
Enzymes that degrade proteins
What do lysosomes need to function
And how is this achieved?
Acidic pH
Proton pump brings H in lysosomes from cytosol
What are the 9 essential AA
Phenylalanine
Valine
Threonine
Tryptophan
Isoleucine
Methionine
Histidine
Leucine
Lysine
