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Molecular Bio - Exam I > Lect. 13 - Intracell Vesicular traffic > Flashcards

Lect. 13 - Intracell Vesicular traffic Flashcards

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1
Q

What 2 major functions does the coat perform?

A

concentrates select proteins in a specialized patch for transport; molds the vesicle to form basketlike lattice that deforms the membrane and gives shape to the vesicle

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2
Q

make up of clatherin subunit

A

3 large and 3 small polypeptide chains that form a 3-legged structure called triskelion

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3
Q

triskelion

A

assemble into a basket-like structure of hexagons and pentagons that form coated pits on the cytosolic side of membrane

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4
Q

adaptor proteins on clatherin coated vesicles

A

form a second layer under the clatherin and trap various transmembrane proteins including receptors for soluble cargo

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5
Q

assembly of clathrin coat

A

introduces a curvature in the membrane which leads to the formation of coated buds

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6
Q

PI (phosphoinositides) role

A

can undergo rapid cycles of phosphorylation and dephosphorylation at the 3’, 4’, and 5’ positions; they control recruitment and binding of proteins to specific organelles/domains and regulate vesicle trafficking

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7
Q

what part of the PIs are recognized by proteins?

A

headgroups

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8
Q

dynamin

A

protein that assembles a ring around the clatherin bud; contains a PIP2 binding domain and GTPase domain

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9
Q

PIP2 binding domain on dynamin

A

tethers the protein to membrane

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10
Q

GTPase domain on dynamin

A

regulates rate of vesicle pinching

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11
Q

pinching

A

brings the 2 cytosolic sides of the membrane together and allows them to fuse

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12
Q

aside from forming a ring around the clathrin vesicle, what does the dynamin do?

A

recruits other proteins that distort the lipid bilayer (ex. lipid modifying enzymes)

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13
Q

what chaperone is uses ATP to peel off the clathrin coat?

A

Hsp 70

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14
Q

Rab proteins

A

monomeric G protein that direct vesicle to specific spots on the target membrane

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15
Q

SNARE proteins

A

mediate fusion of vesicle w/ membrane

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16
Q

how is specificity in targeting of vesicles achieved?

A

by surface markers on vesicles and complementary receptors on target membrane

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17
Q

what regulated the activity of Rab?

A

GTP hydrolysis

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18
Q

what is Rab bound to in the inactive form?

A

GDP (soluble form)

19
Q

what is Rab bound to in the active form?

A

GTP

20
Q

What keeps Rab in the inactive form?

A

binding to Rab-GDP dissociation inhibitor (GDI)

21
Q

what keeps Rab in the active form?

A

interaction w/ Rab-GEFs. tightly bound to a membrane

22
Q

Rab effectors

A

motor/tethering proteins that is present on the target membrane that the active form of Rab binds to

23
Q

Rab1

A

ER and Golgi complex

24
Q

Rab2

A

cis Goli network

25
Q

Rab3A

A

synaptic vesicles, secretory vesicles

26
Q

v-SNAREs

A

single polypeptide; found on VESICLE membrane

27
Q

t-SNAREs

A

2-3 proteins; found on TARGET membrane

28
Q

interaction b/w the v and t forms of SNAREs

A

allow them to wrap around eachother to form a bundle; lock the two membranes together

29
Q

what proteins are packaged into COPII?

A

newly synthesized

30
Q

where do COPII coated transport vesicles bud off from?

A

from the ER exit sites

31
Q

what chaperones are involved in misfolded proteins to keep them retained in the ER

A

BiP or calnexin

32
Q

homotypic

A

fusion of vesicles from SAME compartment

33
Q

heterotypic

A

fusion of vesicles from DIFFERENT compartments

34
Q

vesicular tubular clusters

A

fused structures resulting from vesicles that have released from the ER and fused

35
Q

COPI

A

vesicular tubular clusters bud off to form smaller vesicles that are coated w/ COPI to return proteins to the ER

36
Q

what is the retrieval pathway dependent upon?

A

ER retrieval signals

37
Q

what is the retreival sequence present in the ER membrane?

A

KKXX sequence

38
Q

what is the retrieval sequence present in soluble proteins?

A

KDEL sequence

39
Q

KKXX signal

A

interacts w/ COPI and packaged into COPI-coated vesicles

40
Q

What is needed for soluble proteins to package them into COPI-coated vesicles?

A

KDEL receptor

41
Q

golgi apparatus

A

collection of flattened, membrane-enclosed compartment (cisternae); plays important role in protein glycosylation; each golgi stack has 2 faces: cis/entry and trans/exit

42
Q

Cis Golgi Network (CGN)

A

network of fused vesicular tubular clusters arriving from ER. Proteins and lipids enter Golgi via CGN

43
Q

Trans Golgi Network (TGN)

A

region that allows exit of proteins and lipids to next step of secretory pathway

44
Q

which face of the golgi apparatus is closer to the ER?

A

cis face

Molecular Bio - Exam I (9 decks)

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