Keratins Flashcards
Do keratins form hetero- or homo-dimers?
Heterodimers
Which types of keratin (types 1 and 2) are:
a) acidic
b) basic-neutral
Type 1 keratins are acidic
Type 2 keratins are basic-neutral
Which keratins are primarily expressed in basal keratinocytes in stratified epithelial of the skin and mucosae?
Keratins 5 and 14
Which cells express keratin 7?
Apocrine glands and Merkel cells
Where is keratin 15 expressed?
Basal epithelial cells and hair bulge (in stem cells)
During epidermal differentiation, keratinocytes detach from the basal layer, migrate suprabasally and become post-mitotic. Which keratins are expressed as the cells migrate and keratins 5 and 14 are down regulated?
Keratins 1 and 10
Which epidermal layers express keratin 2?
Upper stratum spinosum and stratum granulosum (marker of advance keratinocyte differentiation)
Which keratin is found in the suprabasal cells of the follicular outer root sheath, hair follicle medulla, sebaceous gland, fetal epidermis and in nail bed and nail matrix epithelia?
Keratin 17
What binds intermediate filaments to desmosomes?
Desmoplakin
What binds intermediate filaments to hemidesmosomes?
- BPAG1e (bullous pemphigoid antigen-1 epithelial) also called BP230
- Plectin
What does filaggrin do?
It gives strength and organisation to the cell by aggregating keratin filaments during collapse of keratinocytes and formation of the corneocyte during epidermal cornification.
Where are keratin associated proteins predominantly expressed?
Hair follicles and other hard cornified structures like the claw
In epidermolytic hyperkeratosis of Norfolk Terriers, there is a mutation of which keratin?
Keratin 10
Basal epidermolysis bullosa simplex in Friesian-Jersey cattle is associated with a mutation near which keratin gene?
Keratin 5
Chesapeake Bay retriever dogs that developed skin lesions consistent with ectodermal dysplasia skin fragility syndrome in humans had a mutation affecting which protein?
Plakophillin 1
How many keratin tetramers (protofilaments) make up an intermediate filament?
8
The cytoskeleton is formed of which three main filamentous polymer proteins?
Microfilaments
Intermediate filaments
Microtubules
What type of strength do intermediate filaments give?
Intermediate filaments, including keratin filaments, are capable of stretching and elongating under stress and then recovering their shape without rupturing
Hard keratins have higher _____ content in their terminal domains from increased cysteine that allows for additional di-sulfide bonds and covalent protein cross-linking.
Sulfur
Which keratins are associated with the paw pad?
Keratin 6
Keratin 9
Keratin 16
Canine epidermal Langerhans cells and some T-cells appear to also express which plakophilin?
PKP2
What does this image, from a cow with EBS, show?
Aggregated eosinophilic globules of intermediate filaments
