9 Protein Folding Flashcards

1
Q

what is the general process by which insulin is prepared?

A

proteolysis

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2
Q

what is the difference between preproinsuin, proinsulin, and insulin? and where is each found?

A
  • prepro has a signal sequence, an A and B chain, and a C peptide. found inside the cell in a reduced form
  • pro insulin is created by cleaving the signal sequence from preproinsulin. Found in the ER in an exidized state
  • insulin is made by cleaving the C peptide from proinsulin
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3
Q

is preproinsulin oxidized or reduced?

A

-reduced

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4
Q

is proinsulin oxidized or reduced?

A

oxidized

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5
Q

is insulin oxidized or reduced?

A

oxidized

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6
Q

when oxidation occurs, and preproinsulin is turned into proinsulin, what does this allow to happen?

A

the formation of disulfide bonds between the A and B chains, allowing for much greater stability

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7
Q

the cytoplasm of the cell is usually an oxidizing or reducing environment?

A

reducing (this is why preproinsulin is reduced and disulfide bonds are not present (Sulfurs bound to hydrogen)

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8
Q

proteins fold to maxmize what>

A

-weak, noncovalent forces

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9
Q

bone skin and tendon are made up of what type of collagen?

A

Collagen type 1

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10
Q

reticulin fibers are made up of what type of collagen?

A

collagen type 3

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11
Q

what are the two standard repeat sequences found in collagen?

A

Gly-Pro-random

Gy-pro-hydroxyproline

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12
Q

other than proline, what else is hydroxylated in collagen?

A

lysine

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13
Q

what does improper hydroxylation of collagen cause and what causes this?

A
  • scurvy (lack of hydroxylation)

- vitamin C deficiency

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14
Q

what end of collagen begins to fold first? the formation of what begins this process?

A
  • c terminus (in most proteins it is the N, which is synthesized first)
  • disulfide bonds, intra and inter chain
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15
Q

what causes the elongated helical structure found in collagen?

A

steric hinderance between prolinesq

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16
Q

what allows collagen chains to pack so tightly together?

A

so many glycine residues

17
Q

the conversion of procollagen to tropocollagen takes place where?

A

ECM

18
Q

what do tropocollagen spontaneously assemble into and how does this happen?

A
  • fibrils

- has a sticky end that attaches to the next collagen

19
Q

what causes osteogenesis imperfecta?

A

-a glycine in the collagen triple helix region being mutated to a cystein

20
Q

why is osteogenesis a dominant mutation?

A
  • because it is a protein with multiple subunits

- all chains have to be correct for the protein to function

21
Q

explain the mechanism of callagen cross linking

A

the enzyme lysyl oxidase crosslinks lysine or hydroxylysine to produce allysine

22
Q

what is the cause of ehlers-danlos syndrome?

A

caused by either a mutation in a collagen processing gene (heterozygosity ok - recessive) or in the collagen gene itself (heterozygosity not ok - dominant)

23
Q

mad cow, srapie, creutzfield jabos, and kuru are all forms of what?

A

prion diseases

24
Q

what are two ways of acquiring a prion disease?

A

inherit or acquire a missense mutation (CJD)

-coming into contact with the bad form of the protein (new variant CJD)