Lecture 11: Functions and Dysfuction of Protein Processing Flashcards

1
Q

Streptomycin

A
  • prokaryotic 30s subunit binding

- interferes w/fmet-tRNA bindings and 50s association

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2
Q

Clindamycin and erythromycin

A
  • prokaryotic 50s subunit binding

- blocks translocation of ribosome

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3
Q

Tetracycline

A
  • prokaryotic 30s subunit binding
  • blocks aminoacyl-tRNA to ribosomal complex
  • blocks ELONGATION
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4
Q

Chloramphenicol

A
  • prokaryotic inhibitor

- inhibits peptidyl transferase, impairs peptide bond formation

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5
Q

Shiga toxin and Ricin

A
  • eukaryotic 60s subunit binding

- blocks aminoacyl-tRNA

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6
Q

Diphtheria toxin

A
  • eukaryotic inhibitor
  • inactivates GTP-bound EF-2
  • blocks ribosomal translocation
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7
Q

Cycloheximide

A
  • eukaryotic inhibitor
  • inhibits peptidyl transferase
  • impairs peptide bond formation
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8
Q

Puromycin

A
  • eukaryotic/prokaryotic
  • causes premature chain termination
  • enters A site, forms puromycylated (premature chain release)
  • hydrolysis resistant (stops ribosome function)
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9
Q

Silent Mutations, Missense Mutations, Nonsense Mutations, Frameshift Mutations

A

Silent - does not change amino acid

Missense - changes amino acid in protein (no effect or vastly different effect)

Nonsense - codon changes into stop codon (truncated)

Frameshift - OOF (change codon sequence, alteration in AA sequence of protein)

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10
Q

Sickle Cell Anemia

A
  • missense (6th codon in allele of Beta-globin)
  • glutamic acid changed to valine (hydrophilic to hydrophobic)
  • poor oxygen capacity and tend to clog capillaries (deformed RBCs)
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11
Q

Duchenne Muscular Dystrophy

A
  • frameshift (dystrophin gene deletions)
  • little (Becker) or no (Duchenne) dystrophin protein
  • muscle wasting
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12
Q

Cytoplasmic and Secretory proteins go where?

A

Cytoplasmic: cytosol, mitochondria, nucleus, peroxisomes (begin/end on free ribosome)

Secretory: ER, lysosomes, plasma membranes, secretion (begins free ribosome, sent to ER)

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13
Q

Mitochondria Translocation Signal

A

N-terminal hydrophobic alpha-helix signal peptide

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14
Q

Nucleus Translocation Signal

A

Lysine/Arginine rich (KKKRK)

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15
Q

Peroxisome Translocation Signal

A

Serine/Lysine/Leucine (SKL)

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16
Q

ER Lumen Translocation Signal

A

Lysine/Aspartate/Glutamine/Leucine (KDEL)

17
Q

Secretory Vesicle Translocation Signal

A

Trp-rich domain (Tryptophan)

18
Q

Lysosome Translocation Signal

A

Mann 6-P

19
Q

Cell Membrane Translocation Signal

A

N Terminal apolar

20
Q

Signal Recognition Particle (SRP) action

A
  • wraps around ribosome-mRNA-peptide complex (ER tethering)
  • complex has 1-2 basic AA and 10-15 hydrophobic sequence
  • enzymes on lumen side cleave protein to release
21
Q

I Cell Disease

A
  • lysosomal proteins are mannose 6P deficient (not sent to lysosomes)
  • high plasma lvls of lysosomal enzymes
  • failure to thrive, developmental delays, physical manifestations
22
Q

What does Acetylation do and what AA does it affect?

A
  • covalently attaches amine group
  • works on Lys
  • use acetyl CoA as donor
23
Q

What does Glycosylation do and what AAs does it affect?

A
  • adds sugar groups
  • O-glycosylation: Serine, Threonine
  • N-glycosylation: Asparagine, Glutamine
24
Q

What does Phosphorylation do and what AAs does it affect?

A
  • phosphate linked by esterfication

- Ser, Tyr, Thr, Asp, His

25
Q

What do Disulfide bonds do and what AA does it affect?

A
  • covalent linkage of cysteine residues (via -SH)

- Cysteine

26
Q

Post Translational Modifications of Collagen

A
  • modifications important for assembly of collagen
  • ascorbic acid essential for activity for lysyl and prolyl hydroxylases
  • defect in lysyl hydroxylases result in disorders
27
Q

Alzheimer’s Disease (AD)

A
  • form amyloid beta peptide
  • forms plaques (extracellular) and hyperphosphorylation of Tau (intracellular) –> tangles
  • APP and Tau mutations cause familial AD
  • brain aging causes sproadic form
28
Q

Parkinson’s Disease (PD)

A
  • aggregation alpha-synuclein forms insoluble fibrils (Lewy bodies) in dopaminergic neurons in substantia nigra
  • symptoms due to reduced availability of dopamine
  • Mutations (familial form), brain aging (sporadic)
29
Q

Huntington’s Disease (HD)

A
  • Huntingtin gene mutation = CAG triplet repeats
  • forms Polyglutamine repeats (misfold and aggregate)
  • selective death of basal ganglia cells (symptoms)
30
Q

Creutzfeldt-Jakob Disease

A
  • misfolding of prion proteins
  • transmissible: misfolded proteins convert proteins to misfold
  • transmissible spongiform encephalopathies