Epithelium: Cell Junctions

Question 1

Name the asymmetric junction(s)

Answer 1

Hemidesmosome (attach cells to the basal lamina)

Question 2

Name the symmetric junction(s)

Answer 2

(btwn two cells) Tight Junction (occluding junction) Anchoring Junction ( belt desmosomes) Anchoring Junction ( spot desmosomes) Communicating Junction (Gap)

Question 3

Tight Junction (occluding)

Answer 3

No intercellular space -circumferential belts at the apical domain of epthelial cells -links adjacent endothelial cells -regulate the passage of ions between adjacent epithelial cells -

Question 4

Transcellular Pathway

Answer 4

Across the cell controlled by channels and receptors

Question 5

Paracellular Pathway

Answer 5

Between the cells regulated by intracellular contact and CELL JUNCTIONS

Question 6

Actin filaments are seen in what type of Junction

Answer 6

Tight

Question 7

What is anchored to Zo-1 in Tight Junctions

Answer 7

Afadin-nectin complex JAMS

Question 8

What type of dimers do Nectins form

Answer 8

cis-homodimers transhomodimers

Question 9

JAMS (Junctional adhesion molecules) attach to

Answer 9

afadin and ZO-1

Question 10

JAMS determine…

Answer 10

formation of cell polarity

Question 11

Order of Junctions from the Lumen down

Answer 11

Tight (occluding) Zonula adherens (belt) Macula adherens (spot)

Question 12

Tight Junctions ..what interacts with F-actin

Answer 12

occludin claudins JAMS

Question 13

What components of the tight junction are seen in freeze fracture?

Answer 13

Occludin and Claudins

Question 14

What type of junctions are show from top to bottom

Line 1

Line 2

Line 3

Answer 14

Tight Junction

Zonula adherens

Macula adherens

Question 15

What type of Junction is this?

Answer 15

Tight Junction (freeze fracture) occludin and claudins

Question 16

What type of Junction is #2

What is inside this intercellular space ?

Answer 16

Tight Junction

Occludin

Claudins

JAMS

Nectins

Question 17

What type of Tight Junctions are part of the immunoglobin family of Cell Adhesion Moleculess?

Answer 17

Nectin and JAMS

Question 18

Occludin and Claudin are part of what family of proteins?

Answer 18

Tetraspanins

Question 19

What part of Tight Junctions are actin Linkers?

Answer 19

ZO

Question 20

Tight Junctions separate which two domains?

Answer 20

Apical and Basolateral membrane domains

(prevent free diffusion of lipids and membrane proteins between them)

Question 21

Tight Junctions regulate …

Answer 21

Paracellular Pathway of fluid and solutes (kidney blood filtration)

Question 22

Nectin and JAMS form homodimers through what bonds

Answer 22

disulfide bonds

Question 23

What type of filaments are associated with tight junctions?

Answer 23

Actin (microfilaments)

Question 24

Freeze Fracture

Answer 24

Creates artifical (FACE)

Protoplasmic (wear bumps are seen) where occuludin and claudins seen

Extracellular face (where pits are seen)

results from spitting membrane across hydrophic core

uses heavy metals to coat the cell

Question 25

Occludin is attached to what ZO

Answer 25

ZO2

Question 26

Clauddin is attached to

Answer 26

ZO 4

Question 27

Belt desmosome Zonula adherens

Answer 27

Afadin-nectin complex plaques (desmoplakin, plakoglobin (gamma catenin), plakophillin) \*anchor\* catenin ( alpha, beta, gamma) go wit cadherins connect to actin cadherins ( desmocollins and desmogleins)

Question 28

What is seen in both tight junctions and belt desmosomes?

Answer 28

Afadin-nectin complex

Question 29

Plaques ( belt desmosomes)

Answer 29

Anchor where cytoplasmic domains of cadherins attach to desmoplakin by plakglobin and plakophillin

Question 30

Belt Desmosomes

Answer 30

belt like actin filaments (interaction of cadherins with catenins) wide extracellular space

Question 31

Belt Cadherins

Answer 31

atttaches to cytoplasmic plaques on cystolicface of plasma membrane 1. desmocollins 2. desmogleins (1 &3 are in epidermis, if issue the pemphigus foliacus)

Question 32

Pemphigus Foliacus

Answer 32

Blistering Disease issue with Desmogleins 1 & 3 (affects epidermis)

Question 33

What are the types of juntions seen?

Answer 33

Top is Tight Junction Bottom is belt desmosome ( can tell because of hte actin filaments but the extracellular space is further apart then the tight )

Question 34

What are the anchoring desmosomes?

Answer 34

Spot Belt Hemidesmosome

Question 35

Name a communicating Junction?

Answer 35

Gap

Question 36

Name an occluding Junction?

Answer 36

Tight

Question 37

Spot desmosome macula adherens

Answer 37

Keratin/ tonomfilaments/ intermediate filaments Plaques ( plakoglobin, plakophillin, desmoplakin) Cadherins (desmocollins and desmogleins) add strenth and rigidty to epithelium layer

Question 38

What is anchored to desmoplakin in spot desmosomes?

Answer 38

Intermediate filaments

Question 39

Differences between belt desmosome and spot desmosome?

Answer 39

spot desmosome has intermeidate filaments (anchor directly to plaque) and no catenins

Question 40

What type of desmosomes are seen in intercalated discs?

Answer 40

spot desmosomes

Question 41

Role of Plakophillin

Answer 41

In plaues (spot and belt desmosomes) recruit protiens to the plasma membranes

Question 42

Disorder with Desmoglein (cadherin)

Answer 42

striate palmoplantar keratoderma (hypotrichosis)

Question 43

Issue with desmoplakin (plaque)

Answer 43

ARVC, woolyhair

Question 44

Issue with Plakoglobin

Answer 44

Naxos Disease ARVC, wooly hair palmoplantar keratoderma

Question 45

In this picture of a spot desmosome what is the top line pointing to?

Answer 45

intermediate filaments

Question 46

Bullous Phemphigoid

Answer 46

autoimmune disease of the skin BLISTER deals with hemidesmosomes Antibodies to BPAG1 or BPAG2 results in detachment of hemidesmosome fromt he basal lamina

Question 47

Hemidesmosomes

Answer 47

Asymetric BPAG1 and BPAG2 Integrins (beta 4 alpha 6) +pectin Laminin 5 Intermediate filaments (anchored to the plaque) (inner cytoplasmic plate) Plaque (DIFFERENT TYPE-NO DESMOPLAKIN, NO PLAKOPHILLIN AND NO PLAKOGLOBIN) Inner cytoplasmic plate (IF) outer cytoplasmic plate ( link hemidesmosome to basal lamina with lamisn and integrin) aids with stability

Question 48

Gap Junctions | (communicating junctions)

Answer 48

Link adjacent cells Connexon: formed by 6 connexins surrounding a central channel Inner channel: allows direct passage of small signaling molecules (calicum and camp) between adjacent cells (helps with coordinating cell responses) hyrophiliic inner channel

Question 49

What junctions tend to have a clustering tendancy?

Answer 49

Gap junctions

Question 50

What junctions are seen in heart muscle cells?

Answer 50

Gap Junctions conduct electricity

Question 51

Issue with Connexin 26

Answer 51

cochlea (deafness)

Question 52

Issue with conexin 32

Answer 52

charcot marie tooth demyelinating neuropathay 1 X linked issue with Schawn Cells

Question 53

Connexin 50

Answer 53

cataracts (blindness)

Question 54

Connexin 43 and 45

Answer 54

Bone cells osteoclast/osteoblast skeletal defects

Question 55

Role of Basement membrane

Answer 55

supporting sheet epithelia

Question 56

Integrins mediate

Answer 56

cell-matrix interaction because of binding affinty to RGD domain in laminin and fibronectin (which are proteins of ECM)

Question 57

Basal Lamina

Answer 57

laminin iv collagen entactin (nidogen) proteoglycans (heparn sulfate)

Question 58

Reticlar Lamina

Answer 58

collagen fibers (III) supports basal lamina with connective tissue

Question 59

Things that are PAS POS

Answer 59

collagens mucus (goblet) glycocalyx glycoproteins (pituitary gland) basement membrane

Question 60

Laminin

Answer 60

basal lamina 3 disuflfide linked polypeptide chains (alpha beta gamma) binding sites for cells surface receptors (integrins), type IV collagen, nidogen

Question 61

Fibronectin

Answer 61

glycoprotein two identical chains joined by disulfide linkage close to C terminal Two types Cellular -produced by fibroblas (ECM) Plasma- produced by hepatocyes (bloodstream)