Exam 2 Post-Translational Modification

Front 1

what is the chemical modification of a protein after it has been translated by a ribosome?

Back 1

post-translational modification

Front 2

post-translational modification occurs within the ... and ...

Back 2

ER
Golgi

Front 3

purposes of post-translational modification:
-extends ... of the protein by attaching to it other functional groups
-changes ... of an AA within the protein
-produces necessary ... in the protein
-controls or ... of the protein

Back 3

-range of functions
-chemical nature
-structural changes
-regulates function

Front 4

proteins destined for the extracellular matrix, RER, SER, Golgi, lysosomes, and peroxisomes must be threaded through the ... membrane first

Back 4

RER

Front 5

These nascent (newly formed) proteins begin with an N-terminal .../signal peptide (13-36 hydrophobic residues) recognized and bound by ..., which in turn binds to an ... within the ER membrane

Back 5

-signal sequence
-signal recognition particle (SRP)
-SRP receptor

Front 6

The protein is targeted to the RER when the SRP meets joins with the ...

Back 6

SRP receptor

Front 7

When the signal sequence is cleaved by a signal peptidase, it is the ... in modification

Back 7

1st step

Front 8

the 4 types of post-translational modifications that can occur to proteins in cells are:
-addition of ...
-addition of other ... or ...
-changing the chemical nature of ...
-major ... changes

Back 8

-functional groups
-proteins or peptides
-amino acids
-structural

Front 9

New functional groups may be added to individual amino acids ... the polypeptide chain, or added directly to the peptide ... and C- and N-terminal ends

An example is the addition of selenium to cysteine forming ...

Back 9

-within
-backbone

-selenocysteine

Front 10

post-translational modifications of AAs result in over # different forms of AAs in the body.

modification of AAs is a specific ...-mediated process

Back 10

200
enzyme

Front 11

purposes of modified amino acids:
-... of protein
-... or ... the proteins in membranes
-... protein's association with another proteins
-target protein for ...

Back 11

-regulate activity
-target or anchor
-enhance
-destruction

Front 12

there are (few/many) post-translational modifications of proteins

Back 12

many

Front 13

glycosylation involves the addition of a ... to a protein, forming a ...

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sugar
glycoprotein

Front 14

common sugars used for glycosylation are ..., galactose, fucose, mannose, ...(N-acetyl-galactosamine), ... (N-acetyl-glucosamine), and sialic acid

Back 14

glucose
GaINAc
GlcNAc

Front 15

The 2 types of glycosylation are ... (in which the sugar is attached to the -OH group of serine, threonine, or tyrosine), and ... (in which the sugar is attached to the -NH2 group of asparagine)

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O-glycosylation
N-glycosylation

Front 16

5 purposes of glycosylation:
-makes proteins more ...
-allows proteins to bind to ...
-... of proteins to different cellular locations
-allows recognition of ... proteins (targets for destruction)
-reduces ... of newly formed proteins by blocking proteases (protects from destruction)

Back 16

-hydrophilic
-receptors
-targeting
-misfolded
-proteolysis

Front 17

different types of glycosylation occur in different regions as the protein moves from the ... through the ...

Back 17

RER
Golgi

Front 18

What is this post-translational modification called?
-addition of a 15-carbon farnesyl group (can anchor proteins to membranes) or 20-carbon geranylgeranyl group (derived from cholesterol biosynthesis)
-attached to Cys residues in a thioether linkage (-C-S-C-)
-GTP binding proteins often go through this modification after translation

Back 18

prenylation

Front 19

One of the most common protein additions to a newly formed protein is ...

-it is used to label old, damaged, or misfolded proteins for destruction in a proteosome

-forms amide linkages with lysine residues on a protein chain

-multiple of this molecule can bind to the same protein

Back 19

ubiquitin

Front 20

It appears that the linkage ... and the ... linkages determines the fate of the tagged protein by ubiquitin.

Back 20

positions
number of

Front 21

other applications of Ubiquitin:
-can be utilized in ... of certain diseases, particularly diseases that involve abnormal accumulation of protein.
-... of diseases including Alzheimer's, parkinson's, pick's, alcoholic liver disease, and motor neuron disease

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diagnostics
markers

Front 22

-one common structural change in proteins is the formation of .../...
-they are covalent linkages between 2 cysteine residues, forming a cystine moiety
-only occurs in the RER, where ... and oxidizing conditions are present

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disulfide bond/bridges

protein disulfide isomerase (PDI)

Front 23

-the simplest form of modification through proteolytic cleavage is the removal of the initiation codon amino acid ... using a specific amino peptidase enzyme.
-inactive precursor proteins that are activated by removal of polypeptides are called ...

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methionine

pro-proteins (such as the proenzymes are called zymogens)

Front 24

another example of proteolytic processing is with pro-opiomelanocortin.

Following the translation and synthesis of this large protein precursor, smaller ... protein fragments are generated through proteolysis

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active

Front 25

Another protein that is post-translationally activated through proteolysis is ...

-in addition to proteolytic cleavage, disulfide bond formation is extremely important in the formation of active, functional ...

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insulin
insulin

Front 26

If the signal sequence is still attached to the protein, it has the prefix "..." attached

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pre

Front 27

Collogen
-fibrous protein produced by fibroblasts, muscle cells, and epithelial cells
-Type 1 collogen is the most abundant protein in ...
-consists of 3 peptide chains interwoven into a ..., providing great tensile strength to connective tissue
-... pattern (triplet repeat is vital for collagen structure and function)

Back 27

mammals
helix
Gly-X-Pro

Front 28

modifications of collagen occur within the ... of the cell, and includes ... of both proline and lysine residues, glycosylation of hydroxylated residues, ... bond formation, oxidative deamination and crosslinking of lysine residues, and proteolytic cleavage.

Back 28

RER
hydroxylation
disulfide

Front 29

hydroxylation occurs in the presence of ... (or vitamin C), therefore a diet deficient in vitamin C would lead to aberrations in collagen structure (as is the case with scurvy)

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ascorbate

Front 30

oxidative deamination by ... initiates collagen cross linking
-cross link formation (inter- and intra- molecular)
-increases strength, toughness

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Lysyl Oxidase

Front 31

vitamin C deficiency results in impaired ... of proline and lysine residues during collagen synthesis

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hydroxylation

Front 32

what are the 4 main diseases of disruption in collagen synthesis?

Back 32

scurvy
osteogenesis imperfecta
ehlers-danlos syndrome
mankes disease

Front 33

which disease is this?
-genetic mutation resulting in substitution of other amino acid for Gly --> improper collagen folding

Back 33

osteogenesis imperfecta

Front 34

which disease is this?
-genetic disorder resulting in poor absorption and distribution of copper --> reduced activity of copper-containing enzyme lysyl oxidase

Back 34

menkes disease

Front 35

which disease is this?
-genetic mutations in lysyl oxidase or hydroxylase

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Ehlers-Danlos syndrome

Front 36

which disease is this?
-dietary deficiency in vitamin C --> reduced activity of prolyl and lysyl hydroxlase

Back 36

scurvy

Front 37

which disease are these symptoms of?
weakness, anemia, hemorrhage, bleeding gums, gingivitis, corkscrew hair growth, abnormal bone growth (in infants)

Back 37

scurvy

Front 38

which disease is this?
-glycine mutation
-symptoms: common bone fractures (even during birth) "brittle bone disease", curved, malformed bones, blue colored sclera, malformation of teeth, autosomal dominant

Back 38

osteogenesis imperfecta

Front 39

which disease is this?
-mutation in Lysyl Oxidase or Hydroxylase
-symptoms: unstable, highly flexible joints, highly elastic, overly stretchable skin, eye problems

Back 39

Ehlers-danlos syndrome

Front 40

which disease is this?
-impaired copper transport/lysyl oxidase
-symptoms: severe delays in development (presents itself between 2-3 months), failure to thrive, kinky, colorless fragile hair ("pili torti"), neurodegeneration, arterial disease, weakened bones, seizures, low body temperature

Back 40

menkes disease