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Cell Biology
cytoskeleton;cell development
48
Biology
Undergraduate 4
12/13/2011

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Cards

Term
3 kinds of coat proteins? destination?
Definition
  1. Clathrin-coated - go to lysosomes or PM
  2. COP1 - go from CGN to ER
  3. COP2 - go from ER to CGN
Term
general steps of sorting into vesicles? 4!
Definition
  1. cargo proteins bind to sorting signal membrane receptors
  2. transmembrane proteins have a cytoplasmic sorting signal that attaches to extracellular cargo or adaptor proteins
  3. cytoplasmic adaptor proteins bind sorting signal of TMProtein and coat proteins
  4. Coat proteins bind to adaptor proteins or TMP sorting signal to form vesicle
Term
during COP2 vesicle formation, what is does COP2 bind to/ what is the adaptor protein?
Definition
SAR1
Term
2 models of protein movement through golgi?
Definition
  1. Vesicular transport Model - vesicles transport cargo from CGN to cis cisternae to medial to trans cist to TGN
  2. Cisternal Maturation Model - Cisternae are made at CGN and change identity through the backward movement of enzymes through cisternae
Term
How do all these proteins know where to go?
Definition
they have sorting signals = amino acid sequences that direct them to destinations
Term
in the cis golgi what lysosomal enzymes are phosporylated on the 6th carbon of the...
Definition
mannose sugar
Term
constitutively secreted, regularly secreted, and lysosomal secreted vesicles are in the.....vesicles entering the CGN but ....... vesicles leaving the TGN
Definition

same

different

Term
are M6P ligand complexes free to move throughout the TGN?
Definition
yes until their sorting signals start to bind adaptor proteins and coat proteins which concentrate them into a coated pit
Term
Clathrin structure?
Definition
  • triskelion
  • 3 HC and 3 LC
  • the arms overlap to a geodesic dome
Term
what is used to pinch off the membrane to form a vesicle
Definition
dynamin
Term
after the vesicle is pinched off, what happens?
Definition

Clathrin and adaptors uncoat for reuse

uncoating requires ATP

Term
I cell disease?
Definition
  • defect in M6P enzymes in cis golgi
  • all enzymes are secreted instead of being delivered to a lysosome
Term

KDEL receptors have what sorting signal?

M6P receptors?

Definition

KKXX

DXXLL

Term

KDEL receptors function?

M6P?

Definition
  • transport cargo from CGN to RER using COP1
  • transport lysosomal enzymes to existing lysosome or to form a new one
Term

SNARE hypothesis?

tethering

docking

fusion

Definition

tethering - rab G proteins are PMP that bind to specific receptors on membranes; also bind tethering proteins

docking - v snares bind to specific t snares (IMPs) at the target membrane.

Fusion - twisting of snares causing the membranes to fuse

Term

receptor mediated endocytosis (RME)?

cholesterol example

Definition
  1. LDL binds LDL receptor binds with high affinity
  2. sorting signal try-x-x-theta binds to AP2 (adaptor) 
  3. clathrin binds AP2
Term
processing of LDL endosome? 5 steps
Definition
  1. clathrin uncoats
  2. H+ are pumped in to increase pH
  3. LDL receptors lose affinity for LDL
  4. LDL receptors bud from sorting compartment and recycle to the PM
  5. LDL winds up in lysosome where it is degraded and releases cholesterol
Term
how many subunits are in a cross section of MTs
Definition
13
Term
which MT subunit is on plus end? minus end?
Definition
  • plus = beta
  • minus = alpha
Term
how is MT polarity established?
Definition
  • gamma subunit that is attached at MTOC preferentially binds alpha subunit or minus end.
Term
Dynamic instability?
Definition
  • MTs fluctuate between slow polymerization and rapid depolym
  • allows for rapid changes in MT network
  • used in prometaphase to attach to chromosomes
Term
MTs must have what in order to grow?
Definition
a GTP cap
Term
3 motor families?
Definition
  1. dyneins
  2. kinesins
  3. myosins
Term
3 functions of motor proteins?
Definition
  1. bind and hydrolyze ATP
  2. use ATP to create a conformational change to bind to cytoskeletion
  3. change conformation to generate force against the cytoskeleton
Term
what determines the cargo that will be moved?
Definition
tail domain
Term
characteristics of Dynein family?
Definition
  • minus end directed
  • move organelles
  • cilia and flagella
  • attach to chroms?
Term
characteristics of kinesin family?
Definition
  • plus end directed
  • move organelles
  • move chroms?
  • assemble mitotic spindle
Term
kinesin movement mechanism?
Definition
  • 1 ATP/step
  • 1 step = one subunit
  • coordinated mvmt of heads 
Term
actin filament structure; polym
Definition
  • must ahve ATP bound in order to polym
  • plus end polym more than minus end
Term
2 mechanisms of actin based motility?
Definition
  1. myosin motor proteins use ATPases to move PGs
  2. actin polymerization can push against the cell membrane via actin binding proteins
Term
myosin family characteristics?
Definition
  • most are plus end directed
  • bind and hydrolyze ATP to generate force against actin
Term
myosin is activated in dispersion or aggregation?
Definition
  • dispersion
  • detaches from PG during aggregation
Term
what does myosin 2 create
Definition
  • bipolar filaments
Term
steps in crawling locomotion? 4
Definition
  1. actin polymerization pushes cell PM
  2. attachment of PM to substrate via IMP focal adhesion
  3. myosin based contraction to pull tail
  4. cell back to normal
Term
what is the key in leading edge push?
Definition
ARP2/3 - acts like actin plus end as actin polymerizes off of it pushes PM farther.
Term
Prophase
Definition
  • centrosomes duplicate
  • chroms condensed
  • nuclear envelope degenerates
Term
prometaphase
Definition
  • high DI, which makes it easy for MTs to bind kinetochores
  • opposing motor forces and poly/depolym moves the chromatids toward the equator
  • tubulin adds at plus end of short MTs and depolym at plus ends of long MTs
Term
Metaphase
Definition
  • Chromatids are aligned at equator
  • metaphase/anaphase checkpoint makes sure all chromosomes are aligned at equator
Term
Anaphase A
Definition
  • sister chromatids separate and move to opposite poles of the cell
  • KMTs shorten at the kinetochore;Dyneins are localized
Term
Anaphase B
Definition
  • spindle elongates
  • MT plus directed motors help push spindles to the poles
Term
Telophase
Definition
  • chromosomes unwind
  • spindle disassembles
  • nuclear envelope reassembles to form two nuclei
Term
cytokinesis
Definition
  • a contractile ring of actin and myosin constricts the PM like a purse string
Term
what hold sister chromatids together?what cuts them apart during anaphase? what inhibits them until then?
Definition
  • cohesion proteins
  • separase protease
  • securin
Term
spindle checkpoint process?
Definition
  • Mad1 and Bub1 are not attached to a MT therefore they activate Mad2
  • Activated Mad2 will bind Cdc20
  • Cdc20 needs to bind Anaphase promoting complex (APC) in order for it to function
  • therefore anaphase is delayed
Term
2 key parts of APC
Definition
  1. Ubiquinating enzyme - marks for destruction
  2. adaptor protein
Term
what does an uninhibited APC do?
Definition
  • APC ubiquinates securin (inhibits protease) for destruction
  • Separase protease is then fxnal
Term
MPF consists of 2 subunits?
Definition
  • catalytic subunit; cyclin dependent kinase; cyclin causes shape change so cyclin-dependent
  • regulatory subunit; cyclin protein whose levels fluctuate throughout the cell cycle
Term
function of CAK and Cdc25 and wee1 kinase
Definition
  • phosphorylate activating AA
  • dephosphorylate inhibiting AAs
  • phosphorylate inhibiting AAs
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