Sbl - Biochem - Skin Proteins

Front 1

Adhesion mechanisms in epidermal basal cells?

Prickle cells?

What the role of Vitamin A in skin?

Structure of integrins?

Back 1

integrins, hemidesmosomes (cells to basement membrane), and cadhedrins, desmosomes (cells to each other)

Prickle cells use cadhedrins more

skin hydration, promotes synthesis of mucins

obligate heterodimer - 19 A, 8 B

Front 2

Structure of A-keratin? How many types are in skin?

A-keratin to intermediate filament:

Basal cells express which keratin genes?

Spinous layer cells express which keratin genes?

Back 2

parallel dimer, same strand, heptad (7-residue repeat), A's match with D's - 4 types (K5/K14, K1/K10)

parallel dimer --> anti-parallel tetramer (2 vs 2)

Basal - K5, K14

Spinous - K1, K10

Front 3

Gene defect in Epidermolysis Bullosa simplex (blistering of basal cells):

Gene defect in epidermolytic hyperkeratosis:

Back 3

K5, K14 - basal cells break from basement membrane

K1, K10 - K1 - carboxyl end, K-10 - amino end

Front 4

Essentially 2 Vitamin A's stuck together:

Where is B-carotene hydrolyzed to Vitamin A?

What happens in the serum?

Which form is involved in GAG and glycoprotein synthesis?

Back 4

Beta-carotene

mucosal cells

Retinol Binding Protein binds retinol, distributes

retinoic acid

Front 5

Structure of dermal layer?

Properties of the polysaccharide gel:

Structure of hyaluronan?

How is it different from other GAG's?

Back 5

fibrous protein network embedded in polysaccharide gel

hydrated (poly-hydroxy structures are hydrophilic), polyanionic (carboxyl & sulfate groups), molecular sieve, resists compression

disaccharide repeats - 5 billion

no proteins, string of sugars, all carboxyl groups

Front 6

4 major GAG's in skin?

Common structure of GAG's?

Proteins with sugars are IC or EC?

Structure of proteoglycans?

Back 6

chondroitin, dermatan, heparan, keratan sulfate

repeated disaccharides + sulfates attached (polyanionic)

EC

core protein - link tetrasaccharide - GAG

Front 7

Types of collagen in skin:

Type of collagen in basal lamina:

Structure of fibril-forming collagen?

Three categories of collagen?

Back 7

I, III (TQTQ)

IV (TQ)

triple helix - repeating triplets (glycine-X-Y, lots of Pro/Pro-OH

fibril-forming, fibril associated, network-forming

Front 8

Major steps in collagen synthesis:

Back 8

hydroxylation of prolines/lysines
glycosylation (forms tropocollagen - 300 x 1.5 nm)
self-assembly of 3 Pro-A chains
procollagen triple helix formation
procollagen to fibril (10-300 nm)
aggregation to collagen fibers

Front 9

Defect in prolyl hydroxylase:

Defect in lysyl hydroxylase:

Co-factors for these enzymes:

Enzyme that links the tropocollagen fibers together:

Defective lysyl oxidase:

Back 9

Scurvy

Ehlers-Danlos VI

Ascorbate (Vitamin C), Fe 2+ -
absence = decreased CT formation, bleeding

lysyl oxidase (requires Cu 2+, B6)

Ehlers-Danlos V

Front 10

Defect in fibrillin, elastic tissue defects:

crosslinks 4 chains together in elastin:

Binds to collagen, integrins, ECM:

Cell binding site on fibronectin:

Back 10

Marfan's syndrome

desmosine

fibronectin

R-G-D (Arg - Gly - Asp)

Front 11

Defect in Type I collagen, brittle bones:

Type I collagen defect, prevents pro-removal, easily bruised, hyperextensible:

Fragile skin, blood vessels, Type III collagen defect:

lysyl oxidase defect, lysyl hydrolase defect, poor wound healing, hyperextensible:

Back 11

Osteogenesis imperfecta

E-D VII

E-D IV

oxidase - E-D V, hydrolase E-D VI