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MCM II > Lec 2 Protein processing > Flashcards

Lec 2 Protein processing Flashcards

1
Q

Structure of mRNA

A
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2
Q

Name of 5’ cap

A

7-methylguanosine

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3
Q

general structure of tRNA

A

cloverleaf

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4
Q

Crucial to tRNA’s function

A

2 regions of unpaired nucleotides.

Anti codon loop (pair with complementary codon in mRNA)

3’ CCA terminal region binds aa that matches codon

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5
Q

aa attach to stem or leaf of clover leaf in tRNA

A
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6
Q

what is an Aminoacyl tRNA

A

complex of tRNA with AA

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7
Q

What activates AA in aminoacyl tRNA’s

A

aminoacyl tRNA synthetases (each unique)

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8
Q

What are the steps of activating AA on tRNA

A
  1. Aminoacyl tRNA synthetase catalzyes addition of AMP to COOH end of AA]
  2. AA transfered to cognate tRNA
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9
Q

what are ribosomes made of

A

proteins and rRNA

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10
Q

Difference between prokaryotic and eukaryotic ribosomes? plus why does this matter?

A
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11
Q

What are the sites on the ribosomal complex

A

Acceptor site

peptidyl site

empty site

(APE)

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12
Q

What are the roles of the sites on the ribosomal complex

A

A-where mRNA codon exposed to receive aminoacyl tRNA

except the met tRNA

P- where aminoacyl tRNA is attached

E- location occupied by empty tRNA before exiting ribosome

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13
Q

Three steps of translation

A
  1. initiation
  2. elongation
  3. termination
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14
Q

Translation Initiation

A
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15
Q

Elongation in translation

A
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16
Q

Termination in translation

A
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17
Q

What makes protein synthesis more efficient?

A

Polysomes- Clusters of ribosomes simultaneously translating a single mRNA molecule (each synthesizing a polypeptide)

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18
Q

The energy expenditure of initiation elongation and termination

A

Initiation- hydrolysis of one GTP

Elongation- hydrolysis of two GTP per aa

Termination- hydrolysis of one GTP

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19
Q

Streptomycin

A

binds to 30s subunit (bacteria) to disrupt initiation of translation. Binding fmet-tRNA interferes with 30s subunit association with 50S subunit

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20
Q

shiga toxin and Ricin

A

binds to 60s subunit to disrupt elongation (EUK) block entry of aminoacyl-tRNA to ribosomal complex

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21
Q

clindamycin and erythromycin

A

bind to 50s subunit to disrupt translocation of ribosome. erythromycin commonly used to treat purtussis.

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22
Q

tetracyclines

A

bind to 30s subunit to disrupt elongation (blocks entry of aminoacyl-tRNA to ribosomal complex)

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23
Q

peptidyl transferase

A

activity is housed in the large subunits

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24
Q

diphtheria toxin

A

inactivates EF2-GTP and inhibits elongation (ribosomal translocation) (EUK) (of the listed is in Humans)

25
Q

chloramphenicol

A

inhibits peptidyl transferase (prok/mitoch)

26
Q

Puromycin (*)

A

causes premature chain termination

resembles 3’ end of aminoacylated tRNA

enters A site and adds to chain

forms a puromyclated chain leads to early release

resistant to hydrolysis

27
Q

two types of protein sorting

A

cytoplasmic and secretory pathway

28
Q

Cytoplasmic pathway destinations

A
  1. cytosol
  2. mitochondria
  3. nucleus
  4. peroxisomes

(synthesis begins and ends on free ribosomes in cytoplasm

29
Q

Secretory pathway destination

A
  1. ER
  2. lysosomes
  3. plasma membranes
  4. secretion

(tranlsation begins on free ribosomes but terminates on ribosome sent to ER)

30
Q

Cytoplasmic translocation signal

A

No signal present it will stay in the cytoplasm

31
Q

Mitochondrial protein signal ( translocational signal)

A
32
Q

Mitochondrial protein import

A

translocation sequences recognized by transporters present in the mitochondrial membrane. proteins passed across via transporter outer membrane (TOM) and transporter inner membrane (TIM). proteins need to be unfolded to fit chaperones called heat shock proteins 70 (HSP70) protect them during unfolding

33
Q

Nuclear translocational signal

A

KKKRK (in picture)

34
Q

Nuclear import mechanism

A

via nuclear pores

small proteins pass through specific pores

large proteins require nuclear localization signals four continuous basic residues (Lys and Arg)

35
Q

peroxisome protein sorting tag

A

SKL

36
Q

Signal sequence for ER lumen

A

KDEL

K-lysine

D-aspartic acid

E-glutamic acid

L-leucine

37
Q

Lysosomal proteins signal sequence

A

Mannos-6-phosphate (only sugar)

38
Q

Membrane proteins

A

N terminal apolar region

(stop trsf)

39
Q

Secretory protein signal sequences

A

Tryptophan domain

40
Q

Secretory pathway general mechanism overview

A
41
Q

I-Cell disease

A

no mannose 6P on lysosomal proteins so cant be brought into lysosome

42
Q

Protein folding big vs small

A

small can self fold

big need proteins called chaperones

utilize ATP

43
Q

chaperonins

A

some proteins havve barrel shaped compartments that admit unfolded proteins and catalyze folding via ATP

44
Q

What happens to an unfolded protein

A
  1. proteases can degrade
  2. clumping
45
Q

Proteolytic clevage

A

Post-translational processing

converts inactive form to active (enzymes)

by unmasking active site (trypsinogen)

46
Q

Glycosylation

A

PTM

addition of sugar residues

O-glycosidic (hydroxyl groups Ser or Thr)

N-glycosidic (always with asparagine phospho dolichol transfered)

O-linked/ N-linked

47
Q

Glycosylation possible disease

A

diabetic cataracts due to lots of glucose which attaches to lens proteins that cant be broken down

48
Q

Phosphorylation

A

formation of ester bond between phosphate and OH of aa

through serine/threonine and tyrosine kinase

regulates enzyme activity and function

(cell growth, proliferation, differentiation, oncogenesis)

uses phosphatases

49
Q

Disulfide bond formation

A
50
Q

Acetylation

A
51
Q

Modifications of collagen

A
52
Q

Types of Post-translational modifications (PTM)

A

COVALENT. types

  1. glycosylation
  2. phosphorylation
  3. disulfide
  4. acetylation

COllagen

53
Q

Alzheimer’s disease

A

Amyloid beta peptide

misfolding/aggregation forms amyloid beta plaques (AB)

hyperphosphorylation of Tau (protein stabalizers)

54
Q

Familial form (AD)

A

mutations in APP and TAu

55
Q

Sporadic form in AD

A

brain aging causes

56
Q

Parkinsons disease

A

aggregation of alpha-synuclein forms fibrils which deposit as lewy bodies in dopaminergic neurons in substantia nigra

reduced dopamine!

57
Q

two forms in parkinsons disease

A

Familial- mutations in AD (alpha synuclein)

Sporadic form- brain aging

58
Q

Huntington’s disease (HD)

A

mutation huntingtins gene results CAG triplet repeats

10-26 goes to 36-121 (causes clumping)

results in polyglutamine repeats which is part of misfold and aggregate. selective death of cells in basal ganglia

59
Q

Creutzfeldt-Jakob disease (HD)

A

misfolding prion proteins

Transmissible- converts normal to misfolded form

transmissible spongiform encephalopathies (TSEs)

spongiform- filled with holes

mad cow disease

MCM II (11 decks)

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