Kaplan Biochem Ch 4 Flashcards Preview

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Flashcards in Kaplan Biochem Ch 4 Deck (100)
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91

gamma carboxylation produces

produces Ca2+ binding sites

92

prenylation

addition of frankly or geranylgeranyl lipid groups to certain membrane-associated proteins

93

hydroxyproline

- AA unique to collagen
- produced by hydroxylation of proudly residues at the Y positions in pro collagen chains as they pass through the RER

94

post translational modifications of collagen (9 steps)

1. prepro-alpha chains containing hydrophobic signal sequence are synthesized by ribosomes attached to the RER
2. the hydrophobic signal sequence is removed by signal peptidase in the RER to form pro-alpha chains
3. selected prolines and lysine are hydroxylated by prolyl and lysyl hydroxylases. These enzymes (located in the RER) require ascorbate (Vit C). Def of Vit C = scurvy
4. Selected hydroxylysines are glycosylated
5. Three pro-alpha chains assemble to form a triple helical structure (procollagen) which can now be transferred to the Golgi. Modification of oligosaccharide continues in the golgi
6. Procollagen is secreted from the cell
7. the pro peptides are cleaved from the ends of pro collagen by proteases to form collagen molecules (also called tropocollagen)
8. collagen molecules assemble into fibrils. Cross-linking involves lysyl oxidase, an enzyme that requires O2 and copper
9. fibrils aggregate and cross-link to form collagen fibers

95

Type 1 Collagen:
- Characteristics
- tissue distribution
- associated diseases

- Characteristics: bundles of fibers, high tensile strength
- tissue distribution: bone, skin, tendons
- associated diseases: OI, EDS

96

This enzyme cross-links collagen molecules to assemble them into fibrils. It requires what?

collagen molecules assemble into fibrils. Cross-linking involves lysyl oxidase, an enzyme that requires O2 and copper

97

Type 2 Collagen:
- Characteristics
- tissue distribution
- associated diseases

- Characteristics: thin fibrils, structural
- tissue distribution: cartilage, vitreous humor
- associated diseases: none

98

Type 3 Collagen:
- Characteristics
- tissue distribution
- associated diseases

- Characteristics: thin fibrils, pliable
- tissue distribution: blood vessels, granulation tissue
- associated diseases: EDS Type 4, keloid formation

99

These enzymes (located in the RER) require ascorbate (Vit C).

- prolyl and lysyl hydroxylases
- these hydroxylate selected proline and lysine residues in collagen

100

Type 4 Collagen:
- Characteristics
- tissue distribution
- associated diseases

- Characteristics: amorphous
- tissue distribution: basement membrane
- associated diseases: goodpasture syndrome, alport disease, epidermylosis bullies