Chapter 13 - Intracellular Vesicular Traffic

Front 1

cargo

Back 1

membrane components and soluble molecules

Front 2

defining a compartment

Back 2

composition of its enclosing membrane, combination of selective markers

Front 3

coated vesicles

Back 3

transport vesicles containing distinctive cage of proteins covering their cytosolic surface

Front 4

purpose of coated vesicles - two

Back 4

- concentrates specific membrane proteins in a specialized patch, thereby selecting the appropriate molecules for transport
-molds the forming vesicle

Front 5

three main types of coated vesicles

Back 5

clathrin - Golgi and plasma membrane
COPI and COPII - ER to Golgi, early in the secretory pathway

Front 6

triskelion

Back 6

clathrin subunit formed by three large and small polypeptide chain

determines the geometry of the clathrin cage

Front 7

adaptor proteins

Back 7

form a discrete second layer of the coat positioned between the clathriin cage and membrane

bind clathrin to the membrane

specific for a different set of cargo receptors

Front 8

coincidence detector - three requirments

Back 8

bind cytoplasmic tails of cargo receptors

interact directly with curved phospholipid bilayer

bind specific phosphorylated PIPs

Front 9

PI vs PIP

Back 9

phosphatidylinositol - PI

phosphoinositides - PIP

interconversion is highly compartmentalized

PI and PIP kinases and phosphatases

recognized by protein domains that discriminate between the different phosphorylated forms, and thus recruit domains to mebrane

Front 10

dynamin

Back 10

GTPase domain, PIP domain which tethers the protein to the membrane

recruits other proteins to site, directly distorts lipid membrane by recruitment of lipid modifying enzymes

Front 11

Hsp70 role in uncoating

Back 11

uses ATP hydrolysis to peel off the clathrin coat

Front 12

coat recruitment GTPase

Back 12

usually found in high cytosolic concentrations in GDP inactive form

recruits coat proteins when GTP bound form is present

when GTP bound is hydrolyzed = coat disassembly

Front 13

Rab proteins

Back 13

GTPase - monomeric

direct the vesicle to the specific spots on the correct target membrane

identifies membrane type and guides vesicular transport between them

Front 14

GDI

Back 14

Rab-GDP dissociation inhibitor

keeps GDP bound Rab soluble in the cytosol

Front 15

Rab effectors

Back 15

bound by Rap proteins once on membrane and facilitate vesicle transport, membrane tethering, and fushion

can be:

motor proteins
tethering proteins
interact with SNARES

same Rab protein can bind to multiple effectors

Front 16

SNARE proteins

Back 16

transmembrane proteins involved in vesicle fushion, usually in complementory sets V and T

Front 17

V SNARE

Back 17

single polypeptide chain found on vesicle

Front 18

T SNARE

Back 18

two or three polypeptide chains found on target cell

often associated with inhibitory proteins which need to be released prior to proper functioning - typically released by Rab and effector proteins

Front 19

trans-SNARE complexes

Back 19

resulting interaction of the T and V SNARE protein helices domain

uses energy of unwrapping of helices to overcome energy barrier

Front 20

NSF protein

Back 20

cycles between the cytosol and membrane catalyzing the disassembly of stable complex of partner SNAREs allowing for repeated use

ATP hydrolysis

Front 21

NSF requirment

Back 21

prevents membranes from fusing indiscriminately