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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
chloramphenicol
inhibits peptidyl transferase (prok/mitoch)
26
Puromycin (\*)
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
two types of protein sorting
cytoplasmic and secretory pathway
28
Cytoplasmic pathway destinations
1. cytosol 2. mitochondria 3. nucleus 4. peroxisomes (synthesis begins and ends on free ribosomes in cytoplasm
29
Secretory pathway destination
1. ER 2. lysosomes 3. plasma membranes 4. secretion (tranlsation begins on free ribosomes but terminates on ribosome sent to ER)
30
Cytoplasmic translocation signal
![]()No signal present it will stay in the cytoplasm
31
Mitochondrial protein signal ( translocational signal)
![]()
32
Mitochondrial protein import
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
Nuclear translocational signal
KKKRK (in picture)
34
Nuclear import mechanism
via nuclear pores small proteins pass through specific pores large proteins require nuclear localization signals four continuous basic residues (Lys and Arg)
35
peroxisome protein sorting tag
SKL
36
Signal sequence for ER lumen
KDEL K-lysine D-aspartic acid E-glutamic acid L-leucine
37
Lysosomal proteins signal sequence
Mannos-6-phosphate (only sugar)
38
Membrane proteins
N terminal apolar region | (stop trsf)
39
Secretory protein signal sequences
Tryptophan domain
40
Secretory pathway general mechanism overview
![]()
41
I-Cell disease
no mannose 6P on lysosomal proteins so cant be brought into lysosome
42
Protein folding big vs small
small can self fold big need proteins called chaperones utilize ATP
43
chaperonins
some proteins havve barrel shaped compartments that admit unfolded proteins and catalyze folding via ATP
44
What happens to an unfolded protein
1. proteases can degrade 2. clumping
45
Proteolytic clevage
Post-translational processing converts inactive form to active (enzymes) by unmasking active site (trypsinogen)
46
Glycosylation
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
Glycosylation possible disease
diabetic cataracts due to lots of glucose which attaches to lens proteins that cant be broken down
48
Phosphorylation
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
Disulfide bond formation
![]()
50
Acetylation
![]()
51
Modifications of collagen
![]()
52
Types of Post-translational modifications (PTM)
COVALENT. types 1. glycosylation 2. phosphorylation 3. disulfide 4. acetylation COllagen
53
Alzheimer's disease
Amyloid beta peptide misfolding/aggregation forms amyloid beta plaques (AB) hyperphosphorylation of Tau (protein stabalizers)
54
Familial form (AD)
mutations in APP and TAu
55
Sporadic form in AD
brain aging causes
56
Parkinsons disease
aggregation of alpha-synuclein forms fibrils which deposit as lewy bodies in dopaminergic neurons in substantia nigra reduced dopamine!
57
two forms in parkinsons disease
Familial- mutations in AD (alpha synuclein) Sporadic form- brain aging
58
Huntington's disease (HD)
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
Creutzfeldt-Jakob disease (HD)
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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