Cell Junctions and Adhesion Flashcards

1
Q

Cell junctions are best observed in

A

Epithelial cells

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2
Q

What are the types of cell junctions?

A
  1. ) Tight junctions
  2. ) Zonula adherens (belt desmosomes)
  3. ) Macular adherens (spot desmosomes)
  4. ) Hemidesmosome
  5. ) Gap (communicating) junctions
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3
Q

Define cell polarityand control the passage of substances between adjacent cells

A

Tight junctions

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4
Q

Have a distribution like a ribbon internally bracing the cells and are associated with actin filaments

A

Tight junctions

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5
Q

An anchorage junction that has a beltlike distribution and is associated with actin filaments

A

Zonula adherens (belt desmosome)

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6
Q

An anchorage junction with a spotlike distribution and is associated with intermediate filaments

A

Macula Adherens (spot desmosomes)

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7
Q

Link the basal domain of an epithelial cell to the basal lamina. Intermediate filaments are associated with a plaque

A

Hemidesmosome

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8
Q

Connect functionally two adjacent cells.

-Formed by connexons

A

Gap junction

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9
Q

Channel-like structures that enable the passage of small molecules

A

Connexons

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10
Q

Gap junctions are not associated with

A

Cytoskeletal components

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11
Q

What are the two cell-cell anchorage junctions?

A

Belt desmosomes and spot desmosomes

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12
Q

What are the cell matrix junctions?

A

Hemidesmosomes and focal adhesions

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13
Q

The transmembrane proteins for the cell-cell anchor junctions (belt and spot desmosomes) are?

Cytoskeletal?

A

1.) Cadherins

Actin (belt) 
Intermediate filaments (spot)
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14
Q

Which two proteins make up tight junctions?

A

Occludins and Claudins

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15
Q

Encircle the entire cell like a belt

A

Tight junctions

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16
Q

The apical domain of a cell faces the

A

Lumen

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17
Q

Tight junctions are composed of “sealing strands” where the two membranes are tightly linked together by lines of

A

Transmembrane proteins

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18
Q

Mediate the adhesion at tight junctions

A

Occludins and Claudins

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19
Q

Occludins and claudins are linked to the actin cytoskeleton through adaptor proteins like

A

ZO-1

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20
Q

Also encircle the entire cell an are positioned right underneath the tight junctions

A

Belt desmosomes

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21
Q

Transmembrane proteins that mediate adhesion at the belt desmosomes

A

Cadherins

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22
Q

In order to function, cadherins need

A

Calcium

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23
Q

Cadherins are linked to the actin cytoskeleton by

A

Catenins

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24
Q

Catenins are made up of

A

α, β, and ƴ/plakoglobin

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25
Q

Binds to cadherin and ƴ-catenin/plakoglobin

A

β-catenin

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26
Q

Binds directly to actin

A

α-catenin

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27
Q

The main proteins holding epithelial cells together in a sheet

A

Cadherins

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28
Q

Important for cell-cell adhesion in the epithelia

A

E-cadherin

29
Q

Contributes to epithelial-mesenchymal transition (EMT) during cancer progression

A

Loss of E-cadherin

30
Q

E-caherin engagement is needed for

A

Tight junction formation

31
Q

Spot-like cell-cell junctions

A

Spot Desmosomes

32
Q

Cadherin family proteins that mediate the adhesion at spot desmosomes

A

Desmocollins and desmogleins

33
Q

Spot desmosomes are linked to which cytoskeletal component?

A

Intermediate filaments

34
Q

Transmembrane proteins that have an α subunit and a β subunit.

-interact with extracellular matrix proteins on the RGD peptide sequence

A

Integrins

35
Q

Integrins are present in actin-linked cell-matrix adhesion sites called

A

Focal adhesions

36
Q

Mediate the interactions between the cells and the basement membrane

A

Hemidesmosomes

37
Q

Mediates the interaction between hemidesmosomes and the basement membrane

A

Integrin α6β4

38
Q

Hemidesmosomes are linked to which cytoskeletal component

A

Intermediate filaments

39
Q

Integrin mediated and are linked to the actin cytoskeleton. These adhesions are not visible under conventional EM, but can be visualized using immuno-EM.

A

Focal adhesions/focal contacts

40
Q

Focal adhesions/focal contacts are important for many cellular processes including

A

Cell migration

41
Q

Serve to coordinate cellular responses

A

Gap junctions

42
Q

Formed by connexon channels, which allow small molecules like Ca2+ and cAMP to pass from cell to cell

A

Gap junctions

43
Q

Connexons are formed by six connexin proteins. Connexon on cell A interacts with connexon on cell B to form the

A

Hydrophilic chanel

44
Q

Connexon permeability is regulated by multiple factors including

A

pH, Voltage, Calcium, etc

45
Q

In gap junctions, there are two plasma membranes close together, similar to tight junctions. However, unlike tight junctions, gap junctions can be

A

Very extensive structures

46
Q

Small molecules can pass between cells through gap junctions. Gap junctions are abundant in

A

Cardiac, smooth muscle, and epithelial cells

47
Q

In connexon channels, high calcium concentration signals

A

Apoptosis

48
Q

Claudin 16 mutation causes an autosomal-recessive renal disorder, familial hypomagnesemia with hypercalciuria and nephrocalcinosis. This affects

A

Tight Junctions

49
Q

P-cadherin mutation causes hypotriosis with juvenile
macular dystrophy, characterized by early hair loss and
progressive degeneration of the central retina. This affects

A

Belt desmosomes

50
Q

Autoimmune disease with antibodies against Desmoglein such as 1-blistering disease affects

A

Spot desmosomes

51
Q

Autoimmune disease with antibodies against BPAG1 such as 2-blistering disease affects

A

Hemidesmosomes

52
Q

Mutations in multiple different connexins causes defects in gap desmosomes that are assoicated with which clinical phenomenon?

A

Deafness

53
Q

There are different ways to get blistering diseases. Blistering diseases are caused by defects in either

A

Spot desmosomes or hemidesmosomes

54
Q

Will cause splitting (vesicles) within the epidermal cell layers

A

Spot desmosome defects

55
Q

Will cause splitting (vesicles) between the epidermis and the underlying basement membrane

A

Hemidesmosome defects

56
Q

Usually found during cell locomotion where dynamic cell-cell and cell-matrix adhesions are needed

A

Non-junctional adhesions

57
Q

Cell adhesion does not only happen at stable cell junctions. During cell locomotion, we also need

A

Dynamic adhesions

58
Q

Transmembrane proteins that bind oligosaccharides

-calcium dependent

A

Selectins

59
Q

Selectins are expressed on the surfaceof

A

Lymphocytes (L-selectin), endothelial cells (E-selectin), and platelets (P-selectin)

60
Q

The extracellular segment of cell adhesion molecules (CAMs) are folded into 2-6 immunoglobin-like domains. As a result, CAMs belong to the

A

Immunoglobin (Ig) Superfamily

61
Q

Immunoglobulin superfamily cell adhesion molecules (IgCAMs) have Ig-like domains on the

A

Extracellular side

62
Q

IgCAMS are NOT dependent on

A

Calcium

63
Q

Play important roles in T cell interactions and binding of leukocytes to activated or resting endothelial cells

A

ICAM and VCAM

64
Q

Slow down and start rolling on the endothelial cell surface through loose adhesion with selectins on the
endothelial cell surface

A

Leukocytes

65
Q

During rolling, integrins on the leukocytes are activated to bind to

A

ICAM and VCAM on endothelial surface

66
Q

These stronger adhesive interactions lead to the arrest of leukocytes on the endothelial cell surface, and the subsequent integrin-mediated migration of leukocytes through the wall of the blood vessel, in between the

A

Endothelial cells

67
Q

The lymphocyte-endothelial cell interaction requires which two types of cell adhesion proteins?

A

Selectins and Integrins

68
Q

High Endothelial Venules (HEVs) in the deep cortex and medulla of lymph nodes allow for the transition of lymphocytes from the blood stream to

A

Lymph Tissue