Protein sorting

Question 1

Protein regulation

Answer 1

regulation of the amount of any one protein in the cells controlled at the level of transcription and translation

Question 2

Ubiquitin

Answer 2

a marker in eukaryotic cells that target cystosolic and nuclear proteins for rapid proteolysis

Question 3

Proteasomes

Answer 3

large, multi-subunit protease complexex that recognize and degrade polyubiquinated proteins.

Question 4

molecular chaperone

Answer 4

proteins that facilitate the folding and translocation of other proteins. keeps protein unfolded until completely synthesized

Question 5

faulty chaperone protein

Answer 5

mad cow disease

Question 6

Free ribosomes

Answer 6

although the synthesis of ALL proteins start on free ribosomes, some continue to be synthesized on free ribosomes, while others finish up translation on these free ribosomes as they become membrane bound

Question 7

branches of protein sorting

Answer 7

cystolic (free)

secretory (free and membrane bound proteins)

Question 8

Targets of cystolic pathway

Answer 8

nucleus, peroxisomes, mitochondria, chloroplasts

Question 9

Targets of secretory pathway

Answer 9

Plasma membrane, secretory vesicles, endosomes, lysosomes, extracellular space, ER and Goldi associated proteins, nuclear membrane proteins

Question 10

what decides where protein goes

Answer 10

protein

Question 11

Rough ER

Answer 11

involved in protein metabolism, entry point for most proteins into the secretory pathway

Question 12

Co-translational proteins

Answer 12

translocation of proteins into ER during their synthesis on membrane-bound ribosomes

Question 13

Signal sequence

Answer 13

signal for ribosome attachment to the RER at N terminus, hydrophobic

Question 14

Signal recognition particles, or SRPs

Answer 14

that recognize and bind to signal sequences, while protin is being translated

Question 15

Signal recognition particle receptors

Answer 15

proteins on membrane of the the ER that bind the SRP

Question 16

translocon

Answer 16

membrane channel composed of secretory proteins through with a signal sequence are transported into the ER

Question 17

BiP

Answer 17

molecular chaperone in ER

Question 18

Signal Peptidase

Answer 18

recognizes signal sequence and cleaves it off growing polypeptide chain

Question 19

GTP binding

Answer 19

triggers the transfer of signal sequence into translocon

Question 20

GTP hydrolysis to GDP

Answer 20

dissociation of SRP from SRP receptor and ribosome-mRNA complex

Question 21

Major protein in Secretroy pathway targeted to the RER

Answer 21

Proteins destined for secretion

Intergral membrane proteins

Question 22

Stop Transfer sequence

Answer 22

Alpha Helix, stops the polypeptide from entering the lumen of the ER and changes the conformation of the translocon channel so membrane opens, releasing the polypeptide chain to the ER membrane

Question 23

Trans and Cis face of Golgi

Answer 23

Cis is closest to ER where proteins enter, while trans is furthest from ER, where proteins exit

Question 24

Vesicle protein coats

Answer 24

Clathrin, COPI, COPII

plays key role in ensuring vesicles reach correct targets

Question 25

Lysosomes

Answer 25

membrane closed organelles that contain an array of enzymes capable of breaking down all types of biological polymers at acidic pH

Question 26

mannose 6 phosphate receptor

Answer 26

binds only mannose 6 phosphate which should be only bound to lysosomal proteins

Question 27

snare hypothesis

Answer 27

fusing of different membrane of vesicle is energy dependent

Question 28

Nuclear pore compexes

Answer 28

establishes nuclear composition as unique form the cytoplasm. gene assembly, RNA processing and ribosome assembly

Question 29

Laminin

Answer 29

Nuclear lamina protein

Question 30

Nucleoporins

Answer 30

pore proteins

Question 31

Nuclear localization signals

Answer 31

specific amino acid sequences that are recognized by transport receptors and direct protein transport from cytoplasm into nucleaus through nuclear pore complex

Question 32

Karyopherins

Answer 32

family of transport receptors

Question 33

Importins

Answer 33

karypherins that direct nuclear import

Question 34

Ran

Answer 34

regulates imprtin cargo complex movement. GTP binding protein

Question 35

Nuclear export signals

Answer 35

specific amino acid sequences that target proteins for export out of nucleus

Question 36

Exportins

Answer 36

members of karyopherin family, similar mechanism to importin