Gms 6001 Cell Signalling

Front 1

What are the 2 types of cell signalling molecules?

Back 1

Front 2

What are examples of intracellular signalling molecules? Where do they bind? Domains of homology w/in the receptor?

Back 2

steroid hormones...bind to cytoplasmic receptors.

Front 3

Explain/diagram how the hormone exerts an effect.

Back 3

Front 4

What are the 3 main motifs seen with signaling of membrane impermanent molecules?

Back 4

a) Bind to a receptor which goes through a conformational change which changes the inside conformation, which affects downstream molecules. (e.g. G protein coupled receptors)
b) Bind to receptor which opens an ion channel. Ions enter cell and affect downstream molecules. (e.g. nicotinic acetyl choline receptor, NMDA receptor- most important signaling ion is Calcium)
c) Bind to receptor which cross-links the receptor. Cross-linking of receptors results in activation of downstream molecules. (e.g. receptor tyrosine kinases, TGFβ family receptors).

Front 5

Describe Ras.

Back 5

Front 6

What is MAP kinase?

Back 6

A major cytoplasmic protein that becomes phosphorylated following growth factor or mitogen stimulation; also phosphorylates microtubule assoc. proteins MAP2 and tau. Thus, it's both a major pro kinase and a major pro kinase substrate.

Front 7

Where is MAP kinase phosphorylated?

Back 7

On both a Y (185) and a T (183) residue.

Front 8

Describe the classical mammalian MAP kinase cascade.

Back 8

MAP kinase is a major protein kinase activated by phosphorylation on two residues by Map-Erk kinase (MEK).
o
MEK is activated by phosphorylation by c-Raf kinase.
o
c-Raf is activated by phosphorylation by other protein kinases, but only after it is membrane localized as a result of binding to p21-Ras, which only happens if p21-Ras is in the GTP bound form, and is itself membrane localized- to be functional p21-Ras needs to be isoprenylated.

Front 9

Compare and contrast viral (v-) src to c-src.

Back 9

pp-60-Src was the first Tyrosine kinase identified- but EGF, NGF and other growth factor receptors are also tyrosine kinases.

Front 10

What is the evolutionarily conserved pathway involved in tyrosine kinase receptor signaling?

Back 10

Front 11

Describe the EGF signaling cascade.

Back 11

Front 12

Model the activation of a simple Tyr kinase.

Back 12

Front 13

What is a Ptb domain?

Back 13

Found in adapters IRS-1 and 2, 3 and 4, Shc and relatives, DOC-1 and relatives- binds NPXY-PO4 sequences, (not, for example, Y-PO4EEI type sequences like SH2 domains).

Front 14

Describe/diagram how adapter molecules can amplify a signal.

Back 14

Front 15

Describe the EGF receptors.

Back 15

Group of receptors that form heterodimers upon activation. RTK's

Front 16

Name some adapter and effector molecules of the EGFr family.

Back 16

Front 17

Describe the activation of cytokine/interleukin receptors.

Back 17

The kinase and receptor are in different molecules, but otherwise quite similar to RTKs…

Front 18

What are the effector molecules in the cytokine/interleukin receptor pathway? How do they work?

Back 18

The STAT's dimerize when activated and interact directly with DNA.

Front 19

How are cytokine receptors regulated?

Back 19

Front 20

Describe how non-receptor tyrosine kinases work.

Back 20

Src associates with Fak and regulates its activation. Activation of Src family kinases often by CD45, a membrane spanning tyrosine phosphatase. Src family kinase are all inactivated by c-Src kinase (CSK) on a C-terminal tyrosine residue (remember c-Src versus v-Src and Tyr 527?).
Scr and Jak assoc. with receptors and are activated upon dimerization (autophosphorylate one another). Once Src and Jak are activated, they also phophorylate the receptor they're bound to allowing mol. with SH2 domains several binding sites.

Front 21

How do B and T cell receptors work?

Back 21

ITAM's contain conserved Y domains

Front 22

How do protein phosphatases work and what do they do?

Back 22

Turning off the kinases… Protein phosphatases; Human genome has 518 kinases, including 90 tyrosine kinases. More than 130 protein phosphatases are encoded in the human genome, including 107 tyrosine phosphatases. There are receptor and non-receptor tyrosine phosphatases….

Front 23

Give a summary of tyrosine kinase signalling.

Back 23

Front 24

What are some notable features of the structure of p21 Ras (and other small G proteins)?

Back 24

***have the same core structure as G alpha subunit***

Front 25

Where does Ras bind and what are some notable domains of the molecules involved in the Ras signalling cascade?

Back 25

Front 26

Contrast the Rap and Ras pathways.

Back 26

Front 27

What are some similarities of the domains of molecules in the Rap and Ras pathways? Differences?

Back 27

Front 28

What are the main domains in the Rac/Rho/Cdc42 family?

Back 28

PH domain=membrane bound

Front 29

Describe the Map Kinase signaling cascade.

Back 29

Front 30

Describe the Map kinase cascade in terms of the Map kinase kinase kinase, Map kinase kinase, etc.

Back 30

Front 31

What are the 2 conserved residues of the activation loop of Map kinases?

Back 31

Threonine and Tyrosine

Front 32

What molecules feed into the Jnk pathway?

Back 32

small GTPases (Rac, Rho, cdc42), cytokines, growth factors/RTK's,

Front 33

What is adenylate cyclase?

Back 33

2nd messenger; coverts ATP to cAMP

Front 34

What mediates G-pro independent signalling?

Back 34

beta-arrestin signalling to MAPK

Front 35

What are the main players in G-pro coupled receptor signalling?

Back 35

Front 36

What are some key features of aa conservation among the 7 TM of GPCRs?

Back 36

-hydrophobic alpha-helices span membrane
-extracellular N-term and intracellular C-term
-N-linked glycosolation=Asn (extracellular)
-S-S stabilize packing of TM helices
-black aa’s are conserved among receptors
mostly in TM spanning domains
variation in extra- and intracellular domains, loops connecting helices, and N- and C-termini

Front 37

Explain how ligands bind differently to GPCR's based on size and other factors.

Back 37

B) Binder of small molecules
tend to interact with residues in TM-spanning domains (which form a pocket)
C)Binds small peptides; rxn with extracellular loops
D) Subclass of family A; binds to N-term and cleaves it to reveal neo-N-terminus which then becomes the ligand (autolytic, irreversible process)
E) Regulates lg glycoproteins; react with N-terminal regions (too lg to react with extracellular loops)
F) Binds to extracellular domains

Front 38

Describe the binding of retinal to Rhodopsin.

Back 38

-Some TM-spanning domains are kinked (due to conserved Pro)
additional C-term alpha-helix that runs parallel to membrance
TM domains form pocket
-Rhodopsin-retinal covalently linked to helix in TM domain

Front 39

How does Rhodopsin's basal activity differ from the adrenergic receptors?

Back 39

Rhodopsin has no basal activity (on/off switch) whereas the adrenergic receptors have differing levels of basal activity (more like a dimmer).

Front 40

What controls open vs. closed conformations of GPCRs?

Back 40

highly conserved DRY seq in TM 3; R participates in ionic rxn’s with Y

Front 41

Describe the G pro cycle.

Back 41

Preassociation of heterotrimeric G-pro to GPCR
34 receptor catalyzes exchange of GDP for GTP (via disocciating GDP from alpha subunit))
5. Alpha has decreased affinity for beta subunit when bound to GTP
56 irreversible step (cleavage of GTPGDP)
alpha now has increased affinity for beta when bound to GDP
***receptors promote dissocciation of GDP***
-beta/gamma subunits can regulate ion channels

Front 42

What are some effectors that G pro regulate?

Back 42

adenylyl cyclase, Ca channels, c-Src Tyr kinases, RhoGEF, phospholipases, PI3K

Front 43

Describe the G pro subunits.

Back 43

-alpha subunits contain 2 domains- GTP/GDP binding and helical
-easy to separate alpha from gamma, but not gamma from beta
-lipid modifications on alpha and gamma help anchor the protein to the subsurface of the plasma mem.
-I, II, and III yellow regions are ‘switch’ regions that undergo conformational change (to activate or inactivate)

Front 44

Describe the interaction between the G-pro and its GPCR.

Back 44

Front 45

Describe the active vs. the inactive conformation of GPCRs.

Back 45

Cz=carazold; overlaid image
-no consensus seq among GPCR’s=no way to predict what ligands they bind
-an activated receptor can activate >1G-pro

Front 46

Describe the role of RGS.

Back 46

-GTPase activity rate too slow to explain rapidity of inactivation
-RGS binds GTP-bound alpha
RGS have GAP activity and stimulate hydrolysis (terminate signal)
-G alpha 12 and 13 subfamilies are esp. activated by RGS (as well as terminated)
RGS acts diff on diff families of G pro

Front 47

What is the RGS domain responsible for?

Back 47

GAP activity

Front 48

Describe G pro-independent signaling of GPCRs.

Back 48

-Desensitization=less responsibe to agonist
-ser/thr domains become substrates for phosphorylation by GRK
beta arrestins bind the phosphorylation sites to prevent activation
can also act as scaffolds to couple GPCR’s to other signalling pathways (like MAPK)
G pro independent pathway (but beta arrestin dependent)

Front 49

Describe desensitization as it pertains to GPCRs.

Back 49

A: G-pro activation of MAPK pathway and desensitization by beta-arrestin
B: G-pro-independent, beta-arrestin dependent activation of MAPK/ERK
class A arrestin=scaffold for MEK, etc transient ERK released rapidly once phosphorylated to nucleus and regulates transcription
class B arrestin binding of MEK etc. is tight leads to phosphorylation of cytoplasmic elements (for migration, etc.)

Front 50

What family of molecules are TGFbeta receptors?

Back 50

Ser/Thr kinases

Front 51

Describe the SMAD proteins and what each does.

Back 51

Inhibitory SMAD’s prevent R-SMAD from entering nucleus
activated by TGFbeta

Front 52

Describe how dorsoventral polarity is regulated in Drosophilia.

Back 52

-dorsal expressed in nucleus (at bottom) and in cytoplasm (at top)
-the Toll ligand (Spatzle) forms morphogenetic gradient

Front 53

How is the mesoderm in Drosophilia regulated?

Back 53

Need dorsal to have Twist expressed

Front 54

What is the dorsal homolog in mammals?

Back 54

-NF kappa=nuclear factor kappa (kappa=lt. chain)
dorsal in humans

Front 55

Describe the NFkappa-B pathway and function.

Back 55

-p65 and p50 are Nfkappa-like proteins
Ikappa=inhibitoryubiquitinated when phosphorylated

Front 56

Compare and contrast Toll-like receptors and NFkappa-B.

Back 56

-Dif=dorsal
-Spaetzle=ligand responsible for gradient
-defects in pathway=inability to fight infection
pathway of innate immune system
-receptors for specific bacterial ag’s (like lipopolysacc., flagellin, and unmethylated CpG <usually methylated in humans>)

Front 57

What pathway(s) is/are TNF alpha receptors involved?

Back 57

Nfkappa also acts in TNF pathway

Front 58

Where do phospholipase A, C, and D cleave?

Back 58

Phospholipase C involved in the release of ER Ca into the cell. Cleaves IP3 from the DAG in the membrane, IP3 acts as a 2nd messenger that opens a ligand-gated Ca channel in the ER.

Front 59

Describe the membrane lipid cycle.

Back 59

Front 60

Describe the phospholipase C domains and what they do.

Back 60

-PIP2 and DAG produced by phospholipase C
-PH domain=membrane binding
-PLCgamma activated directly by RTK’s due to SH2 and SH3
substrate w/in membrane
Efh=Ca binder
PLCdelta=Ca activated
-PLCbeta activated by GPCR

Front 61

Describe Ca regulation in terms of the receptor and mediator.

Back 61

-beta version of phospholipase C
-DAG stays in membrane due to lipid tail
-IP3=diffusible 2nd messenger
stimulate Ca to enter cells via IP3-gated Ca-channel
PKC pathway activated directly by Ca
localized to membrane by DAG

Front 62

Describe the domains of protein kinase C family proteins.

Back 62

-similar Set/Thr kinase domains
-C1 binds DAG
-C2 binds Ca and phospholipids

Front 63

Describe the C1 and C2 domains.

Back 63

C1 domain is ~50 amino acids
which binds diacylglycerol (DAG),
or phorbol esters. Found in PKC
family enzymes, chimearins, c-Raf1, B-Raf and many other molecules.
C2 is ~130 residues involved in
binding phospholipids in a calcium
dependent manner. Found in PKC
family enzymes, synaptotagmin,
perforin, phospholipase C and many other calcium regulated proteins.

Front 64

Describe calmodulin.

Back 64

-Gly flanked by acidic residue (EF hand)

Front 65

How does calmodulin work?

Back 65

-EF hand titrates level of Ca in cells
as [Ca] increases, conformation of EF hand changes (due to Ca binding)
activates other proteins in this conformation

Front 66

Describe Cam Kinase II.

Back 66

multifunctional Calcium/calmodulin dependent protein kinase- involved in learning and memory…

12-16 enzymes clumped together- once Calcium has activated this complex, each enzyme can keep the others activated- molecular memory!
-has a kinase domain and assoc. domain

Front 67

Describe the different conc. patterns of PI(3,4), (4,5), and (3,4, 5) bis- and triphosphates.

Back 67

-PIP2 usually=PI(4.5) bisphosphate
-PDGF=growth factor
PIP2 stayed pretty constant while other membrane lipids rapidly increased
-how PI3K were discovered (phosphorylate at the 3 position of inositol)

Front 68

Describe the diff. pathways of the 3 diff classes of PI3 kinases.

Back 68

-PI3K puts phosphate on portion 3 of inositol
class I PI3k’s not in yeasts (involved in cell signaling of multi-cellular organisms)
-

Front 69

What are the diff subunits of the PI3 kinase enzymes? What do they do?

Back 69

-catalytic and regulatory domains
-4 enzymes of PI3k in humans
catalytic domain forms heterodimer with regulatory domain
activated by RTK
p110gamma activated by GPCR [activation by RTK and GPC common theme among families]

Front 70

How is PKB (protein kinase B) activated?

Back 70

-PH domain usually involved in membrane binding
require PI3 phosphorylation on the membrane lipid
PH binds the 3-phos

Front 71

Describe the PH domain.

Back 71

PH domain binds many ligands -the one in Akt/PKB specifically
binds PI-3,4,5-P3 and PI-3,4-P2 but not PI-4,5-P2. PH domains of PDK1, Btk and several other proteins do this also, anchoring proteins to membranes in a fashion dependent on activation of PI-3 kinases.
Others bind PI-4,5-P2 such as those in GRK2 and GRK3, PLC enzymes, spectrin, all Dbl family members, many other small G protein regulators and many other proteins - more common in the human genome than SH2 domains.

Front 72

Name what activates the diff kinases (Tyr or Ser/Thr).

Back 72

Front 73

What are some second messengers and what rxn's are they involved in?

Back 73

Front 74

Describe the different cytoskeletal networks.

Back 74

-major cytoskeletal networks
-actin has diff. polymerization states
-microtubules are easily broken
-polarized1 end differs from the other
-IF provide structural integrity
sig. variation

Front 75

What is the structural basis for chemotaxis?

Back 75

-polarized placement of certain signaling molecules
PI3K, PTEN, PIP3, actin, myosin, etc.

Front 76

Describe the general theme of cytoskeletal regulation.

Back 76

****often on exams****
-general theme of cytoskeletal regulation
-active=GTP-bound
Rhonot an efficient GTPase by itself
GAP’s help hydrolyze GTP
**Rho activates WaSP and formins
GEF’s help exchange GDP for GTP
GDP-bound Rho can interact w/GDI that take Rho off membrane (GDI also regulated)
Squiggle is prenylation that anchors Rho to membran

Front 77

What are the major classes of intermed. filaments in mammals and what do they do?

Back 77

Front 78

Which cytoskeletal element is the least dynamic?

Back 78

IF's

Front 79

What is the soluble subunit of IF's?

Back 79

tetramer

Front 80

What triggers disassembly of IF's?

Back 80

phosphorylation

Front 81

What forms specificity of cross-linking of IF's?

Back 81

the termini

Front 82

How are IF's packaged?

Back 82

Front 83

Describe the final 10nm IF.

Back 83

The final 10 nm filament consists of a helical array with 16
Dimers in cross-section. Half of the dimers are pointed in each direction

Front 84

Plot the different cytoskeletal elements as a function of deforming force vs. deformation.

Back 84

***often on exams***
“light bulbs” signal breaks
Doesn’t take much force to deform and break MT’s
IF are flexible but don’t break

Front 85

How do IF's contribute to structural integrity of sheets of cells?

Back 85

Keratin filaments in epithelial cells.The filaments in adjacent cells are indirectly connected through desmosomes. Thus intermediate filaments contribute to the structural integrity not only of individual cells, but also sheets of cells.

Front 86

What are some diseases with defective IF's?

Back 86

ALS (neurofilaments), epidermolysis bullosa simplex (keratins)

Front 87

Describe actin kinetics in vitro.

Back 87

-actin in buffer that promotes polymerization
nuclei stabilize interaction with actin monomers (which otherwise don’t stick- limiting factor)
more actin in sol’n=more nuclei=faster polymerization
adding nuclei speeds up this process
-polymerized=fast-growing and slow-growing ends

Front 88

Describe/graph critical conc. (Cc).

Back 88

Cc=critical conc.
no filaments up until the Cc
at steady-state of Cc, filament conc. Filament conc. Increases as more actin is added
Cc=0.2 uM
~50% of actin is polymerized
conc. Of actin in cells is ~50-100uM
vastly above Cc

Front 89

Describe the Cc's of the pos. and neg. ends of actin. What is treadmilling?

Back 89

-actin is an ATPase
hydrolyzed when incorporated into filament
causes conformational change
-Each end has diff Cc
Cc+=0.12 uM, Cc- = 0.60 uM
-actin shown coming off – end and being added to + end
“treadmilling”
Cc in cell is always above each end
can experimentally fool w/Cc to facilitate additive properties

Front 90

What are some regulatory pathways that prevent actin subunits from binding to a growing microfilament?

Back 90

-1, 2, 3 bind to actin and prevent binding (accounts for high conc.)
-cofilin bind ADP actin
can break up filaments
-profilin increases nucleotide exchange (ADPATP)
-Thymosinbinds ATP actin to prevent polymerization

Front 91

What are some ways microfilaments are modified to prevent polymerization?

Back 91

-modulation of filament ends to prevent polymerization

Front 92

What are 2 theories of how Listeria travels within a cell?

Back 92

-ActA recruits endogenous actin machinery
binds actin sides and triggers polymerization
branching mediated by Arp 2/3

-Brownian-Ratchett hypothesis=Listeria moves by Brownian motion and says actin not attached to Listeria

Front 93

What factors mediate actin branching?

Back 93

-Arp2/3 forms a potent nuclei that promotes extension of filaments
can be inactivated and this is regulated

Front 94

How is WASp activated?

Back 94

-Wiscott-Aldrich syn. Protein (WASp) interact w/diff small GTPases
mediates actin activation/polymerization
WASP can also be inactivated
-RBD=Rho binding domain

Front 95

What regulates monomer addition to a growing actin filament?

Back 95

-formins assoc. w/barbed ends/nuclei
stays assoc. w/barbed end
allows regulated addition of new monomer via conformational change

Front 96

How are formins activated?

Back 96

-formins assoc. w/Rho GTPases and are thus activated
WASP and formins bind profilin
actually Profil-actin being added

Front 97

Describe tubulin.

Back 97

Tubulin array of fibrils
Soluble alpha beta tubulin dimer
Interactions along seam allow modulation
Only beta-tubulin hydrolyzes the GTP to GDP (alpha always GTP-bound)

Front 98

What are some qualities of the tubulin seam?

Back 98

Allows for different formations (singlets, doublets, triplets) that lead to specialized structures (cilia, flagella, etc.). Interactions along seam allow modulation.

Front 99

Describe the orientation and localization of microtubules in a cell.

Back 99

-Pos ends point away from nucleus
-Polymerized from specific locations (vs. diffuse like IF)

Front 100

What is gamma TURC?

Back 100

-gamma TURC associates w/- end of tubulin
-gamma TURC=site for initiation of new MT’s
>similar to ARP2/3

Front 101

What does the graph of the assembly and disassembly of MT's look like in real time?

Back 101

Front 102

Describe the disassembly of microtubules.

Back 102

-GDP-beta-tubulin causes ends to fray which is destabilizing and causes disassembly (this is regulated)

Front 103

What are the role of MAP's in the neuron?

Back 103

-MT’s in axons organize in a crystalline-like array
>MAP’s assist in this process

Front 104

What is EB1?

Back 104

-EB1 binds to seam at ends of MT's
>may contribute to stability of end
-used experimentally as a + end tracker

Front 105

What are 2 molecules that play a role in MT disassembly?

Back 105

-Kinesin are molecular motors that assoc. w/MT’s
>Kinesin-13 destabilize the ends of MT’s
-Stathmin is analogous to cofilin and profilin
>prevents units from being added back to filament

Front 106

Describe the conformation of myosin. What enzymes cleave it? What do they yield? What molecule does myosin use to exert force on actin?

Back 106

-coil is the C-term of myosin
>coil is reminiscent of IF’s
>head hydrolyzes ATP and converts it into physical motion
-papain cleavage=2 free head regions

Front 107

What determines the functional properties of myosins?

Back 107

-diff myosins have diff tails and # of heads
>same motif but diff. functions

Front 108

Describe the mechanics of myosin.

Back 108

-3 states: ATP, ADP+Pi, ADP
>use ATP to cock the motor
>power stroke results from Pi release from GDP+Pi

Front 109

Describe the graphs of the 2 processivity schemes of myosin.

Back 109

-processibity of diff myosins
-Myosin II releases the filament but B doesn’t (b/c it has 2 heads and one is bound at any given time)

Front 110

What are the 2 routes of locomotion utilized by processive myosins?

Back 110

Front 111

How do non-processive motors work to move a vesicle?

Back 111

-org. array of non-processive myosins allow movements
>some will be bound while others aren’t

Front 112

Describe the polarity of different molecular motors.

Back 112

-kinesins=(-) to (+)
-dyneins= (+) to (-)
-myosins= (-) to (+) <usually>
-dyneins and kinesins use MT’s but move on diff. tracks

Front 113

What gives specificity of function to kinesins?

Back 113

-diff coiled coils lend specificity of function

Front 114

Describe the mechanics of kinesin and contrast it to myosin.

Back 114

Motors work in tandem (vs. mysoin)

Front 115

How do dyneins differ from kinesins?

Back 115

-bigger than kinesins
>don’t attach directly to cargo
>uses dynactin complex

Front 116

How does dynein link to cargo?

Back 116

-dynactin complex
***a lot of regulation associated with small GTPases (Rho class)

Front 117

What types of molecular messengers are associated with the ECM?

Back 117

-many growth factors, cytokines, and chemokines are assoc. with the extracellular matrix

Front 118

Describe the different cellular junctions.

Back 118

Front 119

What are the different functions of the cell junctions?

Back 119

Front 120

Describe the components of adherens junctions.

Back 120

-CAM’s of adherens junction=cadherins
>extracellular and cytosolic domains
>allows interaction with environment
>conformational changes upon binding to ligand (like another cadherin)
>specific protein (adapters) interact with cytosolic domain
>trigger polymerization of cytoskeleton, activate kinases, attract scaffold proteins, etc.
>interaction extracellularly leads to intracellular effects
>info can flow from within to extracellular domain also
>adapters allow you to use same adhesion molecule in different ways in different cells

Front 121

Define homo- and heterotypic (as they pertain to cell-cell adhesion molecules).

Back 121

-homotypic interactions=the same type of molecule from different cells interact
-heterotypic=adhesion molecules interacting with different molecules

Front 122

What are some of the adapter proteins in adherens junctions? What does the arrangement of adapter proteins determine?

Back 122

-filaments=microfilament
-arrangement of adapter proteins dictate arrangement of cytoskeletal structure

Front 123

What element stimulates cell adhesion via cadherins?

Back 123

Ca

Front 124

Describe desmosomes.

Back 124

-desmosome
-desmoglein and desmocolin interact with intermed. Filaments
>provide structural strength to cell layer
-plaques are adapters
-there is still a space between cells where small molecules can diffuse

Front 125

Describe the components that regulate tight junctions.

Back 125

-extracellular domains of claudins and occludins zip up
>longer cytoplasmic tail

Front 126

Describe claudins and occludins.

Back 126

-extracellular domains of claudins and occludins zip up
>longer cytoplasmic tail
-involved in tight junctions

Front 127

What dictates how "leaky" a tight junction will be?

Back 127

-mix of occludins and claudins in junction dictates how leaky the junction will be
>can be regulated based on organism’s needs

Front 128

Describe an experimental model that allows you to see transcellular transport.

Back 128

-dye put on one side of cell
>allows visualization of whether transcellular transport is occuring

Front 129

Describe gap junctions.

Back 129

-gap junctions are a good way to recruit actin to allow contraction of cell
>direct connection between cytosol of different cells
-gap junctions only allow the passage of small molecules between cells

Front 130

What determines the diversity of gap junctions?

Back 130

-combo’s of connexins allow for different varieties of gap junctions

Front 131

Give an overview of junctional and nonjunctional cell adhesion.

Back 131