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Histology > Cell Adhesion Molecules and Junctional Complexes (exam 1) > Flashcards

Cell Adhesion Molecules and Junctional Complexes (exam 1) Flashcards

1
Q

Simple, non ciliated columnar epithelium is most likely to be found associated with which of the following

A

Digestive system

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2
Q

Junctional complexes are associated with which cellular domains

A

Basolateral

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3
Q

Transitional epithelium is associated with which system

A

Urinary

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4
Q

Although not common, stratified cuboidal epithelium may be found in which of the following areas

A

Part of the male urethra (also has some stratified columnar)

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5
Q

Lightly keratinized stratified squamous epithelium is characteristic of which of the following locations

A

Vaginal epithelium

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6
Q

What are the two components of the basal lamina

A

Basal lamina, Reticular lamina

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7
Q

What is the structure of basal lamina

A

Type IV collagen, Proteoglycans, Fibronectin, Laminin, Entactin

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8
Q

What type of collagen makes up the Reticular lamina

A

Type III collagen

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9
Q

What are the two major calcium dependent CAMs

A

Cadherin and Selectins

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10
Q

What are the two calcium independent CAMs

A

integrin and Immunoglobin superfamily molecules

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11
Q

how thick is the basement membrane

A

50-80nm thick

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12
Q

what separates an epithelial layer from its connective tissue support

A

Basement membrane

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13
Q

Does Type IV collagen form fibrils

A

No

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14
Q

Does Type I collagen form fibrils

A

Yes

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15
Q

What produces type IV collagen

A

Epithelial cells

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16
Q

What produces type I collagen

A

Fibroblasts

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17
Q

Laminin consists of how many chains

A

3

alpha, beta, gamma

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18
Q

Laminin has binding sites for what

A

Integrins, Type IV collagen, entactin and proteoglycans (heparan sulfate)

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19
Q

what is fibronectin composed of

A

two polypeptide chains cross-linked by disulfide bonds

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20
Q

What are the two forms of fibronectin

A

Cellular (produced by fibroblasts; part of ECM)

Plasma (secreted into bloodstream by hepatocytes)

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21
Q

What does fibronectin have binding sites for

A

Heparin (proteoglycan), Integrins, Collagen, and Fibrin

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22
Q

What produces the cellular form of fibronectin

A

Fibroblasts

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23
Q

What produces the Plasma form of fibronectin

A

Hepatocytes

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24
Q

what do cadherins recognize

A

other cadherins (same or different)

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25
Q

Cadherins are part of what types of junctions

A

Occludens and desmosomes

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26
Q

Selecting stabilize what types of junctions

A

none

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27
Q

integrins stabilize what types of junctions

A

hemidesmosomes

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28
Q

Selectins recognize what

A

Carbohydrates

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29
Q

Integrins bind to/recognize what

A

extracellular matrix molecules

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30
Q

Ig superfamily ligans recognize

A

Integrins

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31
Q

Ig superfamily stabilize what types of junctions

A

none

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32
Q

Classical cadherins typically form what type of dimers

A

cis and trans homophilic dimers

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33
Q

What are the there types of classical cadherins

A

E-cadherins (epithelial)
N-Cadherins (nerves)
P-Cadherins (placenta)

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34
Q

Classical cadherins are a major component in what

A

Calcium-mediated adherens junctions

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35
Q

Nonclassical cadherins include what two groups

A

Desmocollins and desmogleins

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36
Q

Where are desmocollins and desmogleins found

A

found in dsmosomes (macula adherens)

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37
Q

What are the most common types of cadherins

A

E-Cadherins

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38
Q

E-cadherins form dimers via what binding face

A

HVA (histidine-valine-alanine sequence)

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39
Q

Where is the HVA bind face of E-Cadherins found

A

at the tip of extracellular end of cadherin molecule

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40
Q

Calcium ions bind to how many extracellular domains of E-Cadherins to form cis-hemophilic dimers

A

4

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41
Q

loss of e-cadherins are associated with the invasive behavior or what

A

Tumor cells

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42
Q

what are catenins

A

small proteins that link the cytoplasmic end of a cadherin with cytoplasmic actin
serve as a major interface between the cadherins that hold adjacent cells together and the actin cytoskeletons of those cells.

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43
Q

what are the three forms of Catenins

A

Beta, gamma/plakoglobin, and alpha catenin

44
Q

what is the function of beta and gamma/plakoglobin catenins

A

Attache to cytoplasmic end of a cadherin,
beta may also serve as a transcription cofactor
beta is also attached to alpha catenin

45
Q

What is the function of alpha catenin

A

binds directly to cytoplasmic actin

46
Q

how many calciums are required to bind for cadherins to funciton

A

4

one to each of the four domains

47
Q

Which of the CAMs belongs to the lectin group

A

Selectins. They are carbohydrate binding

48
Q

Where is the binding site for carbohydrates occurs at what location in selectins

A

Carbohydrate recognition domain (CRD) at the extracellular end of the selectin

49
Q

Where are the calcium binding sites in selectins

A

Found near the CRD

50
Q

Selectins are involved in the movement of what from the blood to tissues

A

Leukocytes

51
Q

What is extravasation

A

The movement of leukocytes from blood to tissues by selectins

52
Q

how many cellular domains do selectins have

A

3 extracellular domains

53
Q

how many calciums must bind to a selectin

A

2

54
Q

what are P-selectins

A

associated with platelets

55
Q

what are E-selectins

A

Associated with activated endothelial cells

56
Q

what are L-selectins

A

associated with leukocytes

57
Q

What are integrins

A

Glycoprotens that are mainly involved in cell-extracellular matrix interactions

58
Q

What do integrins bind to

A

EMC and cytoskeleton

59
Q

integrins consist of how many subunits and what are they

A

two subunits

1 alpha and 1 beta

60
Q

The EMC domains of interns bind to what molecules in the ECM

A

Fibronectin and laminin

61
Q

What sequence do interns bind to

A

The RGD sequence in fibronectin and laminin

62
Q

Laminin and fibronectin in the basement membrane interact with

A

collagen (including type IV), heparin sulfate proteoglycans, and entactin (nidogen)

63
Q

What is interns function in hemidesmosomes

A

link the basal domains of cells to the ECM via the intracellular monofilaments (intermediate filaments such as keratin)

64
Q

what are Immunoglobulin superfamily

A

Members of this family possess an extracellular segment with one or more folded domains characteristic of immunoglobulins

65
Q

what are the members of the Ig-superfamily

A

N-CAM (neural adhesion molecules)

I-CAM-1 and I-CAM-2 ( I-CAM-1 facilitates transendothelial migration of leukocytes)

66
Q

where are adherents found

A

on the basolateral surfaces of epithelial cells

67
Q

What are adherens

A

molecular complexes that anchor cells together and reinforce the physical integrity of tissues and the cells that make up the tissues

68
Q

What are occludens

A

molecular complexes that establish an impermeable barrier between adjacent cell, prevent paracellular transport and maintain concentration differences between the environments on either side of the epithelial sheets.

69
Q

What are gap junctions

A

composed of molecular pores that enable cells to rapidly exchange ions and small molecules that help coordinate activities among the cells that make up the tissue

70
Q

What is meant by Zonula

A

can be adherents or occludens

  • travel all the way around the circumference of the cell and link all neighboring cells to the central cell.
  • belt-like complexes
71
Q

what is meant by macula

A

a macula is a “spot” or snap-like junction. often referred to as desmosomes (associated with lateral domains of epithelial cells) or hemidesmosomes (associated with basal domains of epithelial cells)
Are associated with intracellular intermediate filaments (monofilaments)

72
Q

Adherens are characterized by what proteins

A

Cadherin (desmogleins and desmocollins)

73
Q

Desmoglein 1 and 2 are found where

A

the epidermis

74
Q

Pemphigus focialceus is caused by what

A

Autoantiboidies to desmoglein 1

75
Q

What cadherin proteins are anchored to cytoplasmic plaques

A

Desmoplakin and Plakoglobin

76
Q

Zonula adherens are associated with what

A

Actin microfilaments

77
Q

Macula adherents are associated with what

A

intermediate filaments (tonofilaments)

78
Q

What cadherins mediate interactions with filaments

A

Desmocollins and desmogleins

79
Q

what are hemidesmosomes

A

anchoring junctions that anchor the basal domain of the epithelial cell to the basal lamina

80
Q

what do hemidesmosomes consist of

A

a cytoplasmic plate associated with intermediate filaments such as keratin
a membrane plaque linking the hemidesmosome to the basal lamina via anchoring filaments (laminin 5) and interns (intern alpha6beta4)
note that at one time, hemidesmosomes were thought to be half desmosomes, with the desmosomes associated with the epithelial cells

81
Q

what are the transmembrane proteins that are associated with Zonula occludens that are responsible for its tight junction

A

Claudins and occludins

82
Q

where do occluding and claudins of zonula occludens attach intracellularly

A

ZO-2 and ZO-3

83
Q

what is the function of JAMs and Nectin in Zonula Occludens

A

members of immunoglobulin superfamily. they are stabilized by disulfide bonds and form cis-homodimers that facilitate cell adhesion
nectin is associated with an intracellular molecule, afadin
JAMs are associated intracellularly with both afadin and with ZO-1

84
Q

Zonula occludens proteins and afadin facilitate interaction with what type of intracellular filament

A

Actin

85
Q

what are focal adhesions

A

spots that anchor the cell to the extracellular matrix via integrins

86
Q

how do focal adhesions differ from desmosomes

A

intracellular attachment is not to monofilaments such as keratin but to actin filaments via connecting proteins

87
Q

how can focal adhesions be very stable or degrade easily

A

the extracellular portions of the interns may be folded close to the plasma membrane and unattached to the ECM
cytosolic signals may cause the intern heads to unfold and attach to ECM components such as fibronectin or laminin

88
Q

gap junctions are composed of what

A

connexons

89
Q

how many connexins comprise a connexon

A

6, forming a hexagonal structure with a hollow center

90
Q

Connexons facilitate movement of molecules up to what diameter

A

1.2nm

91
Q

are connexons often clustered into patches

A

yes

92
Q

when do gap junctions close

A

when the calcium ion concentrations are high

93
Q

gap junctions are responsible for what

A

chemical and electrical coupling

94
Q

What are some related pathologies to Gap junction defects

A

Charcot-Marie Tooth neuropathy, Congenital cataracts

95
Q

do tight junctions define cell polarity

A

yes

96
Q

are gap junctions associated with cytoskeletal components

A

No

97
Q

basal lamina is associated with which type of collagen

A

Type IV

98
Q

Type I collagen is associated with what

A

Tendons and ligaments

99
Q

which of the following types of cell adhesion molecules is associated with zone occludens and desmosomes

A

Cadherins

100
Q

desmocollins and desmoglobulins belong to what group of CAMs

A

Cadherins

101
Q

Which of the following serve as a major interface between the cadherins that hold adjacent cells together and their actin cytoskeletons

A

Catenins

102
Q

The extracellular domains of which of the following bind to molecules in the extracellular matrix such as fibronectin and lamina

A

Integrins

103
Q

Which of the following are molecular complexes that anchor cells together and reinforce the physical integrity of tissues and cells that make up the tissues

A

zonula adherens

104
Q

which of the following are molecular complexes that primarily serve to prevent parcellular transport

A

Zonula occludens

105
Q

Which of the following is associated with the basal domains

A

hemidesmosomes

Histology (10 decks)

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