Lecture 2 - CAM & Junctional Complexes

Question 1

Describe the major kinds of cell adhesion molecules
(CAMs) and their role in forming cell-to-cell
complexes.

Answer 1

Ca dependant (selectins and cadherins) and independant (Integrins and IG molecules). Also fibronectin and Laminin in the EC matrix. Occludins and adherens(cadherins)

Question 2

Be able to describe the types of junctional
complexes and relate them to the cohesive nature
of epithelia.

Answer 2

-4 of them HD - intermed - basal, connected to proteins.
MA, - intermed
ZO, ZA - actin

Question 3

basal lamina is defined as ? and contains what 3 things?

Answer 3

a 50-80 nm thick sheetlike extracellular matrix in direct contact with epithelial cell surfaces. The basal lamina results from the self-assembly of laminin molecules with type IV collagen, entactin, and proteoglycans. STains PAS+

Question 4

reticular lamina—formed by ?

Answer 4

collagen fibers—supports the basal lamina and is continuous with the connective tissue.

Question 5

fibronectin has binding sites for ?

Answer 5

integrins, collagen 1-4, heparin sulfate, and fibrin

Question 6

2 types of fibronectin? which are produced by?

Answer 6

1. Plasma fibronectin (produced by hepatocytes) and Cellular fibronectin (by fibroblasts)

Question 7

Laminin has binding sites for ?

Answer 7

type 4 collagen, entactin, proteoglycans, integrin, dystroglycan

Question 8

What produces laminin and collagen IV?

Answer 8

Epithelial cells

Question 9

What produces fibonectin

Answer 9

fibroblasts

Question 10

Which CAM is associated with zonula occludens and desmosomes?

Answer 10

Cadherins

Question 11

Which CAM is associated with binding affinities for Sugar?

Answer 11

Selectins

Question 12

T/F do gap junctions help with Cellular adhesion?

Answer 12

no, they are just assoc. with cellular communication

Question 13

What are your 2 extracellular proteins that are important for structure? and which collagen fibers do they each interact with? also what type of bond links the polypeptide chains of these 2 proteins?

Answer 13

Fibronectin (1-4) and Laminin(4)

disulfide bonds

Question 14

Desmocollins and desmogleins belong to which group of CAM’s?

Answer 14

Cadherins

Question 15

Which CAMs bind to molecules in the extracellular matrix such as fibronectin and laminin?

Answer 15

Integrins

Question 16

which molecular complexes anchor cells together and reinforce the integrity of tissues?

Answer 16

Zonula Adherens

Question 17

Mutation in which CAM causes blistering?

Answer 17

Hemidesmosomes.

Question 18

Do collagen and proteoglycans interact directly or indirectly with the basal domain of epithelial cells?

Answer 18

they interact with the basal membrane, but binding to fibronectin and laminin, so Only Indirect interaction.

Question 19

Because selectins bind carbohydrates, what group do they belong to?

Answer 19

lectin group

Question 20

Zonula Occludins are known for and are a type of?

Answer 20

preventing paracellular transport and are a cadherin, like the adherens.

Question 21

Gap junctions are composed of

Answer 21

6 connexin monomers, in a hexagonal structure with a hollow center that is a hydrophobic intercellular channel

Question 22

Integrins aka focal adhesions are unique in that they?

Answer 22

1. they attached to actin via the EC proteins (fibronectin and laminin) rather than tonofilaments

Question 23

Gap junctions close when what occurs ?

Answer 23

Ca ion concentrations are high

Question 24

Integrins are known to be very stable. whats the likelihood that they may turn over and allow the cell to move?

Answer 24

They can do both, depending on the location and the circumstance.

Question 25

Difference b/w the macula and zonula adherens?

Answer 25

Zonula are belt desmosomes assoc. with actin, and Macula adherencs are spot desmosomes and assoc. with intermediate filaments.

Question 26

Another name for intracellular intermediate filaments?

Answer 26

tonofilaments -

Question 27

Tonofilaments are associated with which 2 junctional complexes?

Answer 27

Hemidesmosomes and Macula adherens

Question 28

How many junctional complexes? name them

Answer 28

4, hemidesmosomes, zonula adherens, zonula occludens, macula adherens

Question 29

What are the 3 major ways Hemidesmosomes are different from the other junct. complexes?

Answer 29

its the only Non symetrical one and in the basal domain and connects to protein molecules in the EC. (integrins are CAM’s not Junct. Comp’s)

Question 30

Cadherins structure is known as a ?

Answer 30

cis homophillic dimer

Question 31

What protein(s) is/are associated with the zonula occludens junctional complex that is/are responsible for the occlusive properties of tight junctions?

Answer 31

Claudins and occludins

Question 32

how do claudins and occludins attach intracellularly to zonula occludens?

Answer 32

through proteins ZO-2 and ZO-3

Question 33

2 transmembrane proteins that are members of the immunglobulin superfamily and facilitate cell adhesion

Answer 33

JAMS (junctional adhesion molec)

Nectin

Question 34

Which intracellular molecule(s) are associated with immunoglobin superfamily proteins JAMS & Nectin?

Answer 34

Afadin - associated with IGS JAMS and Nectin

ZO-1 - assoc. with IGS JAMS

Question 35

3 classes of Selectins?

Answer 35

LEP- Leukocytes, Endothelial, Platelets

Question 36

CRD domain is for what? and whats required for activity progression?

Answer 36

Carbohydrate Recognition Domain for Selectins,

Calcium is required, for binding activity

Question 37

3 locations of cadherins. named for location?

Answer 37

PEN, placenta, epithelial tissues, nerve cells. Our focus on E.

Question 38

The zona adherens is associated with Actin microfilaments through the interactions between?

Answer 38

The cadherins DESMOCOLLINS & DESMOGLEINS with CATENINS

Question 39

For cadherin molecules, referring to their structure being Cis or trans means?

Answer 39

Cis is on the same cell and trans is on 2 different cells.

Question 40

what are catenins?

Answer 40

These are small proteins that link the cytoplasmic end of a cadherin with cytoplasmic actin.

Question 41

How many catenin forms are there?

Answer 41

Three,
Beta, gamma - attaches to cytoplasmic end of cadherin
and alpha. (binds directly to actin.)