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40 Cards in this Set
- Front
- Back
What are the roes of an intermediate filament? |
1. Sustaining stresses and strains 2. Connecting plasma membrane and nuclear compartments 3. Tissue integrity |
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Are intermediate filaments polar? |
No |
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What cells express intermediate filaments? |
Prominent in cells subjected to mechanical stress |
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Within a cell what distinctions between intermediate filaments are there? |
Cytoplasmic and nuclear distinc filaments |
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What is the main role of cytoplasmic cytoskeletal links? |
Mechanical stabilisers and integrators of the cytoskeleton |
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What are IFAPs? Give an example of one. |
IFAPs link microtubules and actin filaments to IFs and also link IFs to each other e.g Plectin |
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What are the types of intermediate filament? |
Types I - VI |
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What specific intermediate filaments fall under Type I & II? |
Keratins |
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What specific intermediate filaments fall under Type III? |
Vimentin & Desmin |
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What specific intermediate filaments fall under Type IV? |
Neurofilaments |
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What specific intermediate filaments fall under Type V |
Laminins |
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What types of Neurofilaments are there? |
NF: L / M / H |
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Where are keratins found? What type of polymer are they? |
In epithelial cells Heteropolymers |
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Where are Neurofilaments found? What type of polymer are they? |
Neurons Homo or heteropolymers |
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Where are vimentins and desmins found found? What type of polymer are they? |
1. i) Mesenchyme ii) muscle iii) glial cells iv) astrocytes 2. Homo and heteropolymers |
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Where are laminins found? What type of polymer are they? |
Nuclei of cells Homopolymers |
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Describe the molecular structure of a general intermediate filament. |
Amino head terminal and Carboxy tail terminal with a central alpha helical rod domain. Critical motifs: 1A, 1B, 2A & 2B which are similar across all IFs. |
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What are the roles of the amino terminal head and Carboxy terminal tail terminals in an intermediate filament? |
1. Amino head is essential for filament assembly 2. Carboxy tail contributes to filament assembly |
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Describe the assembly process of an intermediate filament. |
1. Unstable monomers interact to form a stable parallel, in register, coiled dimer 2. Dimers form staggered anti parallel tetramers - the fundamental subunit 3. Tetramers associate laterally to form loosely packed filaments - protofilaments 4. Further longitudinal extension and radial compaction |
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What is the length of a typical intermediate filament? |
10-14 nm |
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What is the fundamental regulation system of IF assembly? |
Phosphorylation of the serine residues in the amino terminal head domain leads to disassembly |
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What is the most diverse network of intermediate filaments? |
Keratin filaments |
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What are the subdivisions of keratin filaments? How do the types interact? |
Type I - acidic Type II - basic / neutral Form heterodimers |
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Where can the diversity of keratin filaments be observed? |
Diversity is most pronounced in the skin |
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What do keratin filaments attach to? What does this help form? |
Specialised cell junctions - desmosomes. Desmosomes provide link between cells to allow keratin to form a continuous network throughout the epithelium. |
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What keratins are expressed in development? |
K8 and K18 |
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What are the cell layers of the skin epidermis? |
1. Basal 2. Suprabasal 3. Granular |
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What keratin types are present in the basal cell layer? |
K5, K14 and K15 |
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What keratin types are present in the suprabasal cell layer? |
K1 and K10 |
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What keratin types are present in the granular cell layer? |
K2e |
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How does the keratin expression in skin change upon injury? |
K10 is swapped out for K16 |
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What is EBS? What is its molecular basis? |
Epidermolysis bullosa simplex (EBS) Mutations in basal layer keratins - K5 and K14 |
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What is the inheritence of epidermolysis bullosa simplex? |
Autosomal dominant |
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What are the symptoms of EBS? |
Disruption of the keratin network causes cellular rupture and thus blistering of the skin |
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Describe the molecular structure of a neurofilament? |
Triplet protein composed of: NF-L NF-M NF-H |
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What types of IF are found in the nucleus? |
A and B type laminins |
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What is the difference in expression between A and B laminins? |
A laminins are found in call differentiated cells whereas B are in all nuclei |
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What are nuclear laminins responsible for? |
Maintaining nuclear shape |
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What type of 3d structure do laminins form? |
A 2D lattice like meshwork |
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What is laminin binding in the nucleus mediated by? |
Lamin associated proteins (LAPs) |