Endomembranes I

Question 1

what are some examples of secreted proteins

Answer 1

peptide hormones, digestive enzymes, serum proteins, collagen

Question 2

Again, how does trafficking between compartments of the endomembrane system happen?

Answer 2

vessicle trafficking. the vessicles have soluble and insoluble things inside to transport around

Question 3

When a vessicle grabs on the ER what are the four principle things that happen

Answer 3

the cargo is specifically selected; the vessicle gets a budding coat; sometimes they have specific modes of transportation; they recognize and fuse to the final destination

Question 4

how could you use experimental methods to understand the spatial and temporal order of trafficking

Answer 4

fluorescence microscopy of cells that produce a GFP membrane fusion protein; can see mvmt to ER to golgi to plasma membrane

Question 5

how could a transport of membrane glycoprotein be studied?

Answer 5

make extracts of cells and check for sensitivity to endoglycosidase D

Question 6

how could you track location of secreted protein invertase?

Answer 6

you could use conditional (termperature-sensitive) mutants

Question 7

what would be the result of a conditional mutation of Sec61? or SRP

Answer 7

it would be a class A.

Question 8

What is VSV?

Answer 8

vesicular stomatitis virus; it has a glycoprotein that can be tracked. that protein is abbreviated VSVG

Question 9

what happens to VSVG in normal mammalian cells?

Answer 9

modified in the golgi by GlcNAc transferase

Question 10

what does the intercompartment protein transport experiment prove?

Answer 10

you need transport vessicles, cytosol, ATP and GTP to transport stuff

Question 11

coatermer is?

Answer 11

a protein that makes vessicles; examples are COPI, COP2, clathrin

Question 12

Rab is?

Answer 12

small GTP binding protein; subset of the raS SUPERfamily; it conveys vessicle identity that lets it find where to fuse

Question 13

snare is?

Answer 13

long alpha helical vessicle to bring membranes together

Question 14

how does the vessicle figure out what cargo is selected?

Answer 14

The coat!! It selects the cargo, encloses it with v-snares, and makes the bud

Question 15

What vessicle transports from Er to cis golgi?

Answer 15

CopII

Question 16

What is a GTPase associated with CopII? What about GAPs and GEFs?

Answer 16

Sar1 is turned on by GEF, specifically, Sec 12 which is a guanine nucleotide exchange factor. Sar1 is turned off by GAP specifically Sec 23 that dimerizes with sec 24

Question 17

what happens when sar 1 is activated?

Answer 17

it shape shifts into a hydrophobic N-terminus

Question 18

Ancillary proteins does?

Answer 18

it helps proteins (like mr. sar shapeshift) between active and inactive state. Examples of this are GAPs and GEFs

Question 19

Ras superfamily includes?

Answer 19

Arf, Sar 1, Rab, and Ras (we are not talking about this subfamily in this class. these are all subfamilies of the more giant Ras superfamily

Question 20

what does sar1 do?

Answer 20

recruits Sec 23/24 dimer and 24 recruits the cargo. sec 13/31 makes a net (lattice) to trap the cargo

Question 21

now the COPII vessicle needs to bud off. Hows it do that?

Answer 21

coat formation drives the pinching off. thats all we know for now.