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IF role
- 1. cell and tissue integrity
- NO known roll in motility
- 2. IF evolved after divergence of animals from plants
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IF proteins characteristics
- 6 classes
- 1. have similar structure but different amino acid sequences
- 2. have diff N and c terminal domains
- 3. have distinct gene expression patterns
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Keratin
acid and basic classes
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Structural IF/protein characteristics
- alpha helices wrap around to form coils
- VERY STABLE in vivo, hard to study b/c no way of disrupting w/out killing cell
- NO ATP/GTP required
- Apolar assembly (Can reassemble after disassembly)
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Keratin and genetics (1st genetic experiment)
- Poison protein mutation: mutant proteins actually caused greater damage than just the knockout affect
- More C terminus deleted: the MORE IF damage
- Blistering phenotype observed in mice with keratin mutants
- Link to EBS: genetic skin disorder
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IF proteins and diseases
- 1. Keratin (epithelial): blistering diseases
- 2. Desmin (muscle): Myopathies
- 3. Vimentin (mesenchymal): None...mouse still viable
- 4. Neurofilaments (nerves): None...associated w/ALS
- 5. Lamins (nuclear envelope): Muscular dystrophy, Progeria..rapid aging
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IF associated proteins
- 1. Plectin: rod shaped, connecting other IFs together, actin and MTs
- 2. Filaggrin: Aggregates keratin on skin surface
- 3. BPAG1: connects Keratin to BPAG2
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Nuclear lamin role
- nuclear stability and integrity
- Also role in gene expression: progeria
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