Protein sorting I

Question 1

the four things that that matter to the cell when it tries to put proteins into a biological membrane

Answer 1

a signal sequence; the receptor for that sequence; the structure of the translocon; the source of energy for transfer

Question 2

how are proteins transported across membranes to get where they need to go?

Answer 2

okay theres too much for one flashcard

Question 3

Cystic fibrosis is an example of ____

Answer 3

genetically mutated protein that is then mis-sorted.

Question 4

what happens in the mitochondria

Answer 4

TCA; electron transport; ATP production

Question 5

three things that are required to uptake proteins

Answer 5

proton-motive force; ATP; cytosolic chaperones

Question 6

tim is?

Answer 6

translocon of inner membrane in mitochondria

Question 7

tom is?

Answer 7

translocon of outer membrane in mitochondria

Question 8

what is the energy source for protein import to the mitochondrial MATRIX

Answer 8

Hsc70 ATPase outside; Hsc70ATPase inside; proton-motive force

Question 9

what is the hallmark feature that encodes for protein import into mitochondrial MATRIX

Answer 9

the targeting sequence is at the N-terminus. its an amphipathic alpha helix about 20-50 residues long, has R and K; charged residues on one side, hydrophobic on the other

Question 10

Translocation of mitochondrial MATRIX proteins is post-translational (t/f)

Answer 10

true. but it is is folded AFTER translocation

Question 11

what is the receptor for protein transport into the mitochondrial MATRIX

Answer 11

Tom20/22 is import receptor in outer mitochondrial membrane; it is put through the outer membrane through tom 40 (general import pore); the inner membrane pore is Tim23/17 which is associated with tim44

Question 12

tim44 recruits who and for what?

Answer 12

matrix Hsc70 that helps keep Mr. protein guy unfolded still (this uses ATP energy)

Question 13

once the polypeptide is threaded into the mitochondrial MATRIX what happens?

Answer 13

the matrix processing protease takes the targeting sequence off. (just like in the ER)

Question 14

cytochrome oxidase is a protein in the inner mitochondrial membrane for ETC. What would its targeting sequence look like?

Answer 14

matrix targeting sequence, but it also has a hydrophobic stop transfer sequence; it hits that spot and gets happy and stops. otherwise, this is the same as the matrix transport.

Question 15

What is the targeting sequence for IMM like ATP synthase?

Answer 15

matrix targeting sequence, but it also has an internal Oxa1 that is a machine to help rethread it through

Question 16

ADP/ATP antiporter is an IMM protein? What is its targeting signal

Answer 16

it DOESNT have the original matrix targeting sequence

Question 17

if you have an oxa1 then…

Answer 17

it gets into the mitocondria the same way, BUT it has an EXTRA sequence that threads the protein through

Question 18

a multiple spanning protein (like ADP/ATP antiporter) uses what translocons to get in?

Answer 18

Tom70 to tell Tom40 what to do: get the thing through the outermembrane; needs Tim54 and Tim22 to get it to span multiple times through inner membrane

Question 19

how do you keep hydrogen peroxide in the peroxisome

Answer 19

it has catalase that breaks it down

Question 20

what is the targeting sequence for peroxisomal proteins?

Answer 20

three amino acids on the carboxy sequence, and are specific to peroxisomes. called PTS1 which codes “SKL”

Question 21

what is the receptor for peroxisomal proteins?

Answer 21

Pex 5 recognizes the SKL and docks with Pex 14; Pex5 remains bound during translocation (unlike ER transport)

Question 22

what translocon is used for peroxisomal proteins?

Answer 22

Pex 10, 2, and 12.

Question 23

what two things are different about peroxisomal protein transport?

Answer 23

it can be folded!! also the PTS1 targeting seqence is NOT cleaved!!

Question 24

Zellweger syndrome defect of

Answer 24

Pex3 and/or Pex1

Question 25

unlike mitochondria, peroxisomes can arise ___ from precursor membranes drived from ___ as well as____

Answer 25

de novo; ER; by division of pre-existing organelles

Question 26

know what zellweger would result in

Answer 26

even though you don’t want to

Question 27

any protein that is to go outside the cell enters the ____

Answer 27

enoplasmic reticulum