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Questions and Answers
Immunoperoxidase staining of keratin K5 is found in the ______ cells of the epidermis.
Immunoperoxidase staining of keratin K5 is found in the ______ cells of the epidermis.
basal
K10 fluorescence staining shows that suprabasal cells are positive, while ______ cells are negative.
K10 fluorescence staining shows that suprabasal cells are positive, while ______ cells are negative.
basal
Intermediate filament attachment sites include ______ and hemidesmosomes.
Intermediate filament attachment sites include ______ and hemidesmosomes.
desmosomes
Epidermolysis bullosa simplex is characterized by blistering skin due to faults in keratin filament ______.
Epidermolysis bullosa simplex is characterized by blistering skin due to faults in keratin filament ______.
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When intermediate filaments fail, various ______ disorders can arise.
When intermediate filaments fail, various ______ disorders can arise.
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Transgenic mice carrying a mutant keratin gene exhibit blistering similar to the human disease ______.
Transgenic mice carrying a mutant keratin gene exhibit blistering similar to the human disease ______.
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Type III intermediate filament proteins like GFAP and desmin are located at ______.
Type III intermediate filament proteins like GFAP and desmin are located at ______.
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In skin, ______ networks link cell to cell in tissues.
In skin, ______ networks link cell to cell in tissues.
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Type ______ includes keratins 1-8.
Type ______ includes keratins 1-8.
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Type ______ consists of lamins, which are important for nuclear structure.
Type ______ consists of lamins, which are important for nuclear structure.
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Intermediate filaments are characterized by their ______ structure, specifically α-helical coiled-coils.
Intermediate filaments are characterized by their ______ structure, specifically α-helical coiled-coils.
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Vimentin is classified under type ______ intermediate filaments.
Vimentin is classified under type ______ intermediate filaments.
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Intercellular adhesion is facilitated by ______ proteins that connect cells to one another.
Intercellular adhesion is facilitated by ______ proteins that connect cells to one another.
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Nuclear lamina is formed by type ______ filaments which provide structural support to the nucleus.
Nuclear lamina is formed by type ______ filaments which provide structural support to the nucleus.
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Charcot-Marie-Tooth disease is an example of a disorder linked to defects in ______ filaments.
Charcot-Marie-Tooth disease is an example of a disorder linked to defects in ______ filaments.
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Type ______ intermediate filaments are found in epithelial cells and contribute to their structural integrity.
Type ______ intermediate filaments are found in epithelial cells and contribute to their structural integrity.
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Cell type-specific expression patterns of intermediate filaments help define ______ identities.
Cell type-specific expression patterns of intermediate filaments help define ______ identities.
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Intermediate filament proteins are robust and can require denaturants to ______ them.
Intermediate filament proteins are robust and can require denaturants to ______ them.
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Keratin intermediate filaments are composed of Type I and Type ______ proteins.
Keratin intermediate filaments are composed of Type I and Type ______ proteins.
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Type I keratin proteins typically have ______ isoelectric points.
Type I keratin proteins typically have ______ isoelectric points.
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Keratin proteins require an equimolar association of Type I and Type ______ for assembly.
Keratin proteins require an equimolar association of Type I and Type ______ for assembly.
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The formation of keratin filaments is a critical aspect of ______ mechanisms in cells.
The formation of keratin filaments is a critical aspect of ______ mechanisms in cells.
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Keratin intermediate filaments can be classified into two families based on their ______.
Keratin intermediate filaments can be classified into two families based on their ______.
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The ______ lamina is formed by keratin intermediate filaments in the nucleus.
The ______ lamina is formed by keratin intermediate filaments in the nucleus.
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Keratins help form a protective barrier in ______ tissues.
Keratins help form a protective barrier in ______ tissues.
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Blistering disorders can arise from defects in keratin ______.
Blistering disorders can arise from defects in keratin ______.
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Keratins such as K8 and K18 are classified as ______ keratins.
Keratins such as K8 and K18 are classified as ______ keratins.
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Keratin proteins are dynamic as ______ keratin is incorporated into filaments.
Keratin proteins are dynamic as ______ keratin is incorporated into filaments.
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The intermediate filament multigene family includes Type I and Type II keratins, both found in ______.
The intermediate filament multigene family includes Type I and Type II keratins, both found in ______.
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Intermediate filaments assemble into ______ dimers, which then form antiparallel tetramers.
Intermediate filaments assemble into ______ dimers, which then form antiparallel tetramers.
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The protein structure of intermediate filaments is essential for ______ resistance but allows for flexibility.
The protein structure of intermediate filaments is essential for ______ resistance but allows for flexibility.
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The nucleoskeletal type of intermediate filaments known as ______ provides structural support to the nucleus.
The nucleoskeletal type of intermediate filaments known as ______ provides structural support to the nucleus.
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Epidermolysis bullosa simplex is caused by defects in keratin filaments, leading to ______ in the skin.
Epidermolysis bullosa simplex is caused by defects in keratin filaments, leading to ______ in the skin.
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Type I and Type II keratins are mainly found in ______.
Type I and Type II keratins are mainly found in ______.
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Type III intermediate filaments are referred to as ______-like and are associated with mesenchymal tissues.
Type III intermediate filaments are referred to as ______-like and are associated with mesenchymal tissues.
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Type IV intermediate filaments are known as ______ and are found in neurones.
Type IV intermediate filaments are known as ______ and are found in neurones.
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Type V intermediate filaments, known as ______, are present in all nuclei.
Type V intermediate filaments, known as ______, are present in all nuclei.
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The nuclear lamina is formed by A- and B-type ______.
The nuclear lamina is formed by A- and B-type ______.
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Intermediate filaments are typically around ______ nm long.
Intermediate filaments are typically around ______ nm long.
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Desmin surrounds the sarcomere in ______ muscle.
Desmin surrounds the sarcomere in ______ muscle.
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The disassembly and reassembly of the nuclear lamina occur during ______.
The disassembly and reassembly of the nuclear lamina occur during ______.
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Lamin proteins cannot co-assemble with cytoplasmic intermediate filaments due to their length and ______ characteristics.
Lamin proteins cannot co-assemble with cytoplasmic intermediate filaments due to their length and ______ characteristics.
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Blistering disorders often result from defects in ______ proteins, which are crucial for skin integrity.
Blistering disorders often result from defects in ______ proteins, which are crucial for skin integrity.
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What type of intermediate filament is specifically associated with mesenchymal tissues?
What type of intermediate filament is specifically associated with mesenchymal tissues?
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Which type of intermediate filament exclusively forms a framework of the nuclear lamina?
Which type of intermediate filament exclusively forms a framework of the nuclear lamina?
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Why can't lamins co-assemble with cytoplasmic intermediate filaments?
Why can't lamins co-assemble with cytoplasmic intermediate filaments?
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In skeletal muscle, which intermediate filament surrounds the sarcomere?
In skeletal muscle, which intermediate filament surrounds the sarcomere?
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What characteristic is true of A- and B-type lamins?
What characteristic is true of A- and B-type lamins?
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What is the primary characteristic of intermediate filaments?
What is the primary characteristic of intermediate filaments?
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Which of the following correctly describes the structure of intermediate filaments?
Which of the following correctly describes the structure of intermediate filaments?
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What type of intermediate filament is associated with the mesenchymal tissues?
What type of intermediate filament is associated with the mesenchymal tissues?
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Which intermediate filament proteins are found in the nucleus?
Which intermediate filament proteins are found in the nucleus?
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Which of the following statements about the intermediate filament multigene family is correct?
Which of the following statements about the intermediate filament multigene family is correct?
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What property of intermediate filament proteins contributes to their robustness?
What property of intermediate filament proteins contributes to their robustness?
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What is the role of cytoplasmic intermediate filaments in the cell?
What is the role of cytoplasmic intermediate filaments in the cell?
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In which type of muscle is desmin predominantly located?
In which type of muscle is desmin predominantly located?
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What characterizes Type I keratin proteins?
What characterizes Type I keratin proteins?
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Which keratin proteins are expressed in mucosal tissues?
Which keratin proteins are expressed in mucosal tissues?
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What is required for the proper assembly of keratin intermediate filaments?
What is required for the proper assembly of keratin intermediate filaments?
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Which keratin proteins are classified as fast turnover keratins?
Which keratin proteins are classified as fast turnover keratins?
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What type of intermediate filament proteins are keratins classified as?
What type of intermediate filament proteins are keratins classified as?
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Which keratin subtype is associated with the corneal epithelium?
Which keratin subtype is associated with the corneal epithelium?
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What structural feature is common to all intermediate filaments?
What structural feature is common to all intermediate filaments?
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In what type of tissues are Type II keratins primarily found?
In what type of tissues are Type II keratins primarily found?
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What role do keratin intermediate filaments play in cells?
What role do keratin intermediate filaments play in cells?
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What happens to keratin when it is incorporated into filaments?
What happens to keratin when it is incorporated into filaments?
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What underlying genetic factor causes the fragility of basal keratinocytes in epidermolysis bullosa simplex?
What underlying genetic factor causes the fragility of basal keratinocytes in epidermolysis bullosa simplex?
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Which keratin type is specifically stained by immunoperoxidase methods in the basal cells of the epidermis?
Which keratin type is specifically stained by immunoperoxidase methods in the basal cells of the epidermis?
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Which structure provides cell-to-cell linkage through intermediate filaments in tissues?
Which structure provides cell-to-cell linkage through intermediate filaments in tissues?
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What type of staining is used to demonstrate keratin K10 in the skin?
What type of staining is used to demonstrate keratin K10 in the skin?
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What is the consequence of mutations affecting the formation of keratin filaments?
What is the consequence of mutations affecting the formation of keratin filaments?
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How are keratins organized in the context of their interaction with intermediate filaments?
How are keratins organized in the context of their interaction with intermediate filaments?
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Which type of intermediate filament proteins are associated with desmosomes?
Which type of intermediate filament proteins are associated with desmosomes?
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What characteristic is unique to type III intermediate filament proteins?
What characteristic is unique to type III intermediate filament proteins?
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The assembly of keratin filaments is essential for which of the following cellular functions?
The assembly of keratin filaments is essential for which of the following cellular functions?
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What is the primary impact of transgenic mice with a mutant keratin gene?
What is the primary impact of transgenic mice with a mutant keratin gene?
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What is the assembly sequence of intermediate filaments?
What is the assembly sequence of intermediate filaments?
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Which of the following statements about the physical properties of intermediate filaments is correct?
Which of the following statements about the physical properties of intermediate filaments is correct?
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What role do heptad repeats play in intermediate filament proteins?
What role do heptad repeats play in intermediate filament proteins?
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Which type of intermediate filament is primarily associated with epithelial cells?
Which type of intermediate filament is primarily associated with epithelial cells?
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What is the significance of the sequence motifs at the ends of the rod domain in intermediate filaments?
What is the significance of the sequence motifs at the ends of the rod domain in intermediate filaments?
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What is true about the polymerization of intermediate filaments in vitro?
What is true about the polymerization of intermediate filaments in vitro?
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How are intermediate filament proteins visualized in scientific studies?
How are intermediate filament proteins visualized in scientific studies?
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What characterizes the structural formation of intermediate filaments?
What characterizes the structural formation of intermediate filaments?
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What differentiates Type III intermediate filaments from others?
What differentiates Type III intermediate filaments from others?
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What is the role of the 'stutter' in intermediate filament assembly?
What is the role of the 'stutter' in intermediate filament assembly?
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Study Notes
Cell Shape and Movement
- Course code: BS31004
- Lecturer: Dr Alan Prescott
- Email: [email protected]
Intermediate Filaments
- Most resilient cell structures
- Withstand significant stress and strain
- Expression patterns vary between cell types
- Large multigene family
- Similar secondary structure: α-helical, coiled-coils
- Cytoplasmic and nuclear networks extending from plasma membrane to nucleus
Major Types of Intermediate Filament Proteins in Vertebrate Cells
| Type of Intermediate Filament | Component Polypeptides | Location |
|---|---|---|
| Nuclear | Lamins A, B, and C | Nuclear lamina (inner lining of nuclear envelope) |
| Vimentin-like | Vimentin | Many cells of mesenchymal origin |
| Desmin | Muscle | |
| Glial fibrillary acidic protein | Glial cells (astrocytes and some Schwann cells) | |
| Peripherin | Some neurons | |
| Epithelial | Type I keratins (acidic) | Epithelial cells and their derivatives (e.g., hair and nails) |
| Type II keratins (neutral/basic) | Epithelial cells | |
| Axonal | Neurofilament proteins (NF-L, NF-M, and NF-H) | Neurons |
Major Classes of Intermediate Filaments in Mammals
| Class | Protein | Distribution | Proposed Function |
|---|---|---|---|
| I | Acidic keratins | Epithelial cells | Tissue strength and integrity |
| Basic keratins | Epithelial cells | Tissue strength and integrity | |
| II | Desmin, GFAP, vimentin | Muscle, glial cells, mesenchymal cells | Sarcomere organization, integrity |
| IV | Neurofilaments (NFL, NFM, and NFH) | Neurons | Axon organization |
| V | Lamins | Nucleus | Nuclear structure and organization |
Intermediate Filament Multigene Family
- Numerous types of intermediate filaments, forming a family
- Pie chart illustrating the variety of intermediate filament types and their relative proportions
Intermediate Filament Proteins
- Robust proteins requiring denaturants for dissolution
- Denaturant removal (e.g., urea) initiates assembly
- No energy required for in vitro assembly
- In vitro assembly involves di- and monovalent cations, physiological pH, reducing agents at room temperature
- Assembly progresses from dimers to tetramers, then higher oligomers
- Heptad repeats in α-helices form coiled coils
- Sequence motifs at either end of rod domain are crucial for assembly
- Small soluble pool of filaments exists
- Filaments are apolar, with subunit exchange throughout the filament
Structure of Intermediate Filaments
- Assembles into parallel dimers, then antiparallel tetramers
- Alpha-helical rod domain with head and tail domains crucial for assembly
Heptad Repeats
- Basis of coiled-coil formation in intermediate filament protein dimers
- Visualized as a helical wheel with a-helices
The Intermediate Filament Multigene Family
- Type I keratin: epithelia
- Type II keratin: epithelia
- Type III vimentin-like: mesenchyme
- Type IV neurofilaments: neurones
- Type V lamins: all nuclei
- Type VI (variable):
Visualization of Intermediate Filament Protein Tetramers
- Visualizing intermediate filament protein tetramers via electron microscopy
Intermediate Filaments Polymerization
- Intermediate filaments polymerize spontaneously and rapidly in vitro
- No need for ATP/GTP, cofactors, or associated proteins during in vitro polymerization
Physical Properties of Cytoskeletal Filaments
- Graph showing the relationship between deforming force and deformation for microtubules, intermediate filaments, and actin filaments, highlighting the relative strength and elasticity of intermediate filaments
Structure and Assembly of Intermediate Filaments
- Demonstrating the structure of intermediate filaments
- Showing the different stages in the assembly process
Keratin Intermediate Filament Proteins
- Type I proteins: acidic isoelectric points/lower molecular weight
- Type II proteins: neutral or basic isoelectric points/higher molecular weight
- Obligate heteropolymers
- Type I and Type II equimolar association for assembly
- Tissue-specific paired expression
Position of Keratins on 2D Gels
- Illustrating the position of keratin proteins on 2D gels based on isoelectric pH (pI) and molecular weight (Mr)
Types I & II : Keratin Filament Protein Families
- Illustrating the different types of keratin proteins and their distribution
- Differentiating by tissue and function
Keratin Intermediate Filaments Dynamics
- Illustrating the dynamics of keratin intermediate filament
- Soluble keratin incorporated into filaments
Immunoperoxidase Staining of Keratin in Skin and Buccal Epithelium
- Visualizing keratin protein in basal cells of epidermis and buccal epithelium via immunoperoxidase staining
K10 Fluorescence Staining in Epidermis
- Fluorescence staining of K10 in supra-basal and basal cells distinguishing between them based on staining
Purification and In Vitro Assembly of Bovine Muzzle Keratins
- Purification procedure and in vitro assembly of bovine muzzle keratins
In Vitro Assembled Keratin Filaments
- Electron micrographs of in vitro assembled keratin filaments
Intermediate Filament Attachment Sites
- Keratin attachments: desmosomes, hemidesmosomes
- Type III IF proteins: desmosomes (GFAP/Desmin), ankyrin (plasma membrane)
Keratins and Desmosomes
- Illustrating keratins and desmosomes in immunofluorescence
Desmosomes and Intermediate Filaments
- Electron micrographs showing desmosomes and intermediate filaments
Intermediate Filament - Desmosome Networks
- Diagram demonstrating how intermediate filaments and desmosomes connect cells in tissues
Epidermolysis Bullosa Simplex
- Skin blistering disorder due to mutations in basal cell keratins (K5 or K14)
- Basal keratinocytes are fragile, causing keratin filament formation defects
When Intermediate Filaments Fail...
- Diagram illustrating the consequences of intermediate filament dysfunction on skin blistering disorders
Transgenic Mice
- Mice with mutant keratin genes exhibit similar epidermis blistering as in human disease epidermolysis bullosa simplex
Different Filament Networks Coexistence
- Microscopic images demonstrating the coexistence of keratin and vimentin filament networks within the same cell
Muscle Intermediate Filaments
- Locations of intermediate filaments (e.g., desmin) in muscle tissue
Desmin Surrounds Sarcomere
- Diagram of desmin surrounding the sarcomere in a skeletal muscle structure
Muscle: Distinct Locations
- Intermediate Filaments in muscle; highlighting specific locations for different intermediate filaments e.g., desmin in muscle fibers
Lamin Intermediate Filaments
- Lamin intermediate filaments are intranuclear
- α-helical/coiled coils of defined length are critical for assembly and function
- Lamins are involved in the nuclear lamina structure
- B type lamins found in all nuclei
- A type lamins found in specialized cells
Intermediate Filaments in the Nucleus
- Types of nuclear lamins and their function in nuclear lamina framework
- Inability of lamins to co-assemble with cytoplasmic filaments
- Disassembly and reassembly of nuclear lamina during mitosis
Lamin Meshwork in Oocyte Nuclei
- Microscopic image illustrating the laminar meshwork within oocyte nuclei
GFP-Lamin B in Live Cells
- Image of GFP-tagged lamin B within live cells
Nuclear Lamina and Cytoplasmic Skeleton
- Diagram illustrating the connection between the nuclear lamina and the cytoplasmic cytoskeleton
Cross-Linked Intermediate Filaments
- Electron micrographs showing cross-linked intermediate filaments within axons (non-helical extension) and glial cells
Neurofilament Protein Structure
- Diagram of neurofilament protein structure with details on NFL and NfH
Quick-Freeze Deep Etch Preparation for Electron Microscopy
- Electron micrograph showing cross bridges in neurofilaments from extended tail domains
Type VI Intermediate Filaments
- Lens-specific intermediate filament proteins and images showing lens tissue at different ages.
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Description
Test your knowledge on keratin biology and the structure of the epidermis with this quiz. Covering topics from immunoperoxidase staining to intermediate filaments and related disorders, this quiz will challenge your understanding of skin cell types and functions. Perfect for students of dermatology or cell biology!
