Cell and Molecular Bio EXAM 3

i am so tired

Enzyme responsible for phosphorylation and effects of phosphorylation

Protein Kinase, activated protein

Long distance cell signaling pathways, involves bloodstream

endocrine

Short distance cell signaling pathway, targets nearby cells

paracrine

“self-signaling,” signaling toward another part of same cell

autocrine

6 important secondary messengers to know

cAMP, cGMP, Ca2+ ions, NO gas, IP3, DAG

JAK and epo live in ____

seperate home

What residue of jak stat pathway is phosphorylated

tyrosine

jak phosphorylates ____

stat

what does stat do?

transcription factor, causes proliferation of RBC

What happens if you delete EpoR

no blood

How to find if gene is upstream/downstream to one another?

knockout + overexpression

ski =

oncogene

overexpression of jak and stat =

oncogene

how to prevent jak/stat overexpression?

siRNA, gene knockdown, or competitive inhibitor of jak

how to naturally stop jak/stat overexpression

dephosphorylation or socs box recruits ubiquitin-polyubiquitination

distinguishing characteristic of receptor tyrosine kinase

has intrinsic cytosolic kinase

what do cytosine kinase need?

recruit jak x2

example of receptor tyrosine kinase pathway

fgf receptor tyrosine kinase

fgf receptor tyrosine kinase characteristics

growth factors, weak binding between receptor and fgf

counselor for fgf receptor and fgf

heparan sulfate (HS), very negatively charged to combat positive fgf and fgfr

other example of receptor tyrosine kinase pathway

epidermal growth factor EGF(2×2)

downstream tyrosine kinase events

GRB2 interacts with SH3, SOS interacts wiht SH3

SH3

interacts with proline rich sequence

What happens after SOS binding? (3)

GDP bound Ras binds SOS, GEF phosphorylates GDP, active Ras dissociates for further signaling

acylated lipid anchored protein

Ras

Phosphorylates GDP

GEF

dephosphorylates GTP

GTPase

What happens after active Ras?

Inactive Raf binds to Ras and is activated

MAP kinase job

proliferation, transcription factor that finds target gene as dimer

what is needed for transcription factors to find dna

HAT, chromatin → euchromatin

Know downstream transcription factors

Wnt signaling

Wnt = signaling moleule, Frizzled = receptor, B catenin = transcription factor

hedgehog signaling

hedgehog = ligand, patch = intermediate receptor, smol = real receptor,

TNF alpha signaling

Nf kappa B phosphorylated and ubiquitination, enters nucleus

Notch signaling

3 types of cytoskeleton

microfilaments (actin), microtubules, and intermediate filaments

thin protrusions that decide direction of migrating cells (contains actin)

filopodia

broad protrusive structure (contains actin and assists with migration)

lamelipodia

anchor made of actin integrin and fibronectin

focal adhesion

cell needs ___ to move around

chemoattractant

1st step of cell locomotion

release protrusion body (filopodia = more efficient)

2nd step of locomotion

protrusion bodies attach to surface target via forming focal adhesion

3rd step loomotion

stress fiber pulls cells forward and deadhesion from previous attachments

polymerization of actin

g-actin

individual polymers of actin

f-actin

ions involved with actin polymerization

mg and ca

actin has ability to bind ____ and ____

ADP, ATP

3 isomers of actin

alpha, beta, gamma

How many subunits in polypeptide of actin?

4

Actin can also be considered a _______

ATPase

polymerization of actin can occurr via _____ _____ with ____

self assembly, atp

T or F f-actin is polar, with one positive end and one negative end

T

How to determine direction of polarity of f-actin?

spray with myosin heads, will form arrowhead shape, pointed end will point towards negative end

How to furth assemble g-actin?

use actin-binding proteins like fibrin, spectrin, actinin, filamin

bridge protein between plasma membrane and actin filament

dystrophin

rate of filament polymerization

nucleation (lag), elongation (log), steady state

rate-limiting step of actin polymerization

nucleation

how to speed up actin polymerization (skip rate-limiting)

provide “seed", provide several nuclei at beginning

Which end of actin grows faster?

positive end

How to measure rate of polymerization of actin at each end?

block one end of actin while other end stays unblocked

how to block positive end

CapZ

how to block negative end

tropomodulin

Why is there so much monomer actin in the body?

sequestered by monomer bindiing proteins

Protein that recognizes ADP bound actin (negative end) and cuts filament

Cofilin

Recognizes ADP monomer actin and exchanges for ATP

Profilin

interacts with ATP bound monomer actin and imprisons them

Thymosin b4

Cytosolic concentration of thymosin b4 is equal to _______

concentration of monomer actin, 0.2 mM

_____ of actin monomers are ready for firing

50%

What is necessary for release of monomers

chemoattractant signal

Receptor pathway for actin

GPCI

fh1 and fh2

how is actin built via fh1 and fh2

Brownian movement (seesaw)

actin nucleator

formin

t or f lamellipodium needs different protein recruited

T

protein needed for lamellipodium

WASp

Lamellipodium creation sequence

mother filament binds arp3 and arp2, wasp binds proteins and recruits daughter filament

angle of mother and daughter

70

which end is driving force for protrusion

positive end

how can actin be hijacked?

certain bacteria (listeria) can move between cells and express protein

listeria protein

rear end ACTa, catches actin monomers and add them to arp2/3 complex

why do bacteria hijack?

push movement forward from actin tail

actin fibers found near _____ sites

endocytic

_____ end is near the neck of endocytic vesicle

positive

protein necessary for fusion of vesicle to plasma membrane

dynamin

classes of myosin

II = 2 heavy 4 light chains, standard, muscle contraction; non-conventional myosin

non-conventional myosin

I, V, VI, XI

common denominator of myosin

bind to actin and ATP, chemical energy converted to mechanical

function of myosin tail (non-conventional)

interact with biological membrane

myosin II tail function

self-assembly, creates bipolar thick filaments

how to visualize function of myosin head?

sever, put on slide with actin and ATP, observe movement with fluorescence

where does myosin move toward?

positive end

myosin XI function in plants

cytoplasmic streaming

myosin V function

workforce for vesicle and organelle delivery

T or F myosin II has a large stride/step size compared to other myosin

F

what is myosin step size correlated with?

length of the neck

Why does having longer neck increase step size myosin

increased swinging angle

Sarcomere components

actin filaments and myosin filaments, z disk, ai zone, h zone, a band, i band

other proteins associated with sarcomere

titin, nebulin

titin function in sarcomere

associated with mysoin, interacts with z disk

nebulin function

associated with actin, controls length of sarcomere