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DBCS 311 > Biochem: Cell Junctions and Adhesions > Flashcards

Biochem: Cell Junctions and Adhesions Flashcards

1
Q

Cell adhesion molecules are ______ proteins. The can bind to a variety of extracellular proteins as well as to other adhesion molecules on adjacent cells. Some have interactions with the cytoskeleton.

A

Transmembrane

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2
Q

Adhesion interaction of binding to another adhesion molecule of a different type

A

Heterophilic

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3
Q

Adhesion interaction of binding to another adhesion molecule of the same type

A

Homophilic

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4
Q

This anchorage junction and defines cell polarity and controls the passage of substances between adjacent cells. It has a BELTLIKE distribution like a ribbon internally bracing the cells cells They are associated with ______ filaments

A

Tight Junctions Actin Filaments

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5
Q

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

A

Zonula Adherens or Belt Desmosome

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6
Q

This anchorage junction has a spotlike distribution

A

Macula Adherens Spotlike Desmosome

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7
Q

Spotlike desmosomes are associated with ______ filaments

A

Intermediate filaments

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8
Q

This anchorage junction links to the basement domain of an epithelial cell to the basal lamina.

A

Hemidesmosome

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9
Q

Hemidesmosomes have _______ filaments The aforementioned filaments in hemidesmosomes are associated with a

A

intermediate Plaque

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10
Q

These COMMUNICATING junctions connect functionally two adjacent cells. They are NOT associated with cytoskeletal components

A

Gap junctions

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11
Q

Gap junctions are formed by _______, channel like structures that enable the passage of small molecules between cells

A

Connexons

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12
Q

These are the symmetrical junctions

A

Tight Junctions, Belt Desmosomes (zonula adherens), desmosomes (macula adherens), and gap junctions

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13
Q

This is the one asymmetrical junction

A

Hemidesmosome

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14
Q

The four important families of cell adhesion molecules

A

Cadherins Selectins Integrins Immunoglobulin-like superfamily

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15
Q

This family of cell adhesion molecules exhibits calcium dependent homophilic binding. There are 40 different ones, 3 of them being most common.

A

Cadherins

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16
Q

This is an epithelial cadherin found along the lateral cell surfaces and is responsible for the maintenance of most epithelial layers

A

E-cadherin

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17
Q

This cadherin is found in the CNS, the lens of the eye, and in skeletal and cardiac muscle.

A

N-cadherin

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18
Q

This cadherin is found in the placenta

A

P-cadherin

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19
Q

This cell adhesion molecules is part of the cadherin family, and anchors epithelial cells together and allows for formation of the tight and stable epithelial layer

A

Desmosomes (or adherens junctions)

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20
Q

The special cadherins in desmosomes are called ______ and ______

A

Desmogleins and desmocollins

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21
Q

The cadherins of zonula adherins (belt desmosomes) are anchored by _______ filaments

A

Actin filaments

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22
Q

The cadherins of macula adherins (spot desmosomes) are anchored by _______ ________ filaments

A

Keratin intermediate filaments

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23
Q

This is an autoimmune disease in which the body generates antibodies against desmoglein 1, causing blisting It disrupts ______ adhesion

A

Pemphigus Foliaceus Keratinocyte adhesion

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24
Q

This is an autoimmnune disease where the body generates antibodies against desmogelin 3, It affects the….

A

Pemphigus Vulgaris Oral Mucosa

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25
Q

This family of adhesion molecules require calcium for binding, but require a carbohydrate ligand

A

Selectins

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26
Q

Each selectin has a carbohydrate recognition domain (CRD) with binding affinity to a specific _________ attached to a protein (glycoprotein) or lip (glycolipid)

A

Oligosaccharide

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27
Q

This selectin is in platelets and activated endothelial cells

A

P-selectin

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28
Q

This selectin is found only in activated endothelial cells

A

E-selectin

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29
Q

This selectin is found in leukocytes

A

L-selectin

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30
Q

The binding for selectins is ______, like for leukocytes moving along the endothelium

A

Transient

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31
Q

In selectins, _______ bound at the sides of the CRD regulates the conformation of the domain and its ability to bind carbohydrates

A

Calcium

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32
Q

This family of cell adhesion molecules is a large family of molecules, consisting of α and β chains.

A

Integrins

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33
Q

There are about __ integrin heterodimers consisting of 17 forms of α and 8 forms of β subunits. (more complex than selectins, etc)

A

22

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34
Q

Integrins conduct outside in and inside out signaling. They communicate from cell to ____ and cell to _____ They have active and inactive states.

A

Cell to cell Cell to matrix

35
Q

Which cells are integrins in? Which cells are they particularly important for? They are also found in this anchorage junction

A

ALL cells Platelets and Leukocytes Hemidesmosomes

36
Q

The α-actinin subunit of integrins bind to _____ The β subunit of integrins binds to ____ (check this)

A

Actin Fibronectin and laminin

37
Q

If a prootein has a ________ in it, it will likely be an integrin

A

RGD (arginine glycine aspartic acid)

38
Q

These contain integrins, they are asymmetrical structures anchoring the basal domain of an epithelial cell to the underlying basal lamina

A

Hemidesmosomes

39
Q

A hemidesmisone consists of an inner cytoplasmic plate associated with…. And an outer membrane plaque linking the hemidesmosome to the basal lamina by __________ and _______

A

Intermediate filaments (also called keratins or tonofilaments) Anchoring filaments composed of lamina 5 and integrin α6β4

40
Q

This is an autoimmune disease where the body generates antibodies to BPAG 1 and 2

A

Bullous Pemphigoid

41
Q

In Bullous Pemphigoid, the antibodies disrupt the ______ and initiate and inflammatory reaction

A

Hemidesmosome

42
Q

In bullous pemphigoid, the disruption of hemidesmosomes separates the ___ and ____, causing blistering

A

Dermis and Epidermis

43
Q

In bullous pemphigoid, a circulating antibody to the BP antigen triggers a local response that induces mast cells to release ______

A

Eosinophil cemotactic factor (which attracts eosinophils)

44
Q

In bullous pemphigoid, ECFs recruit the eosinophils which releases _____, causing the breakdown of anchoring filaments linking the attachment plaque of the hemidesmosome to the basal lamina, developing a blister

A

Proteases

45
Q

Platelets can switch on and off, this specific type is found in blood

A

Platelet Integrins

46
Q

This type of platelet adhesion is integrin independent, occurs on damaged vessel walls

A

Rolling Adhesion

47
Q

This type of platelet adhesion is associated with inside out signaling, aggregated/activated platelets, and fibrinogen

A

Stationary Adhesion

48
Q

This type of platelet adhesion is associated with outside in signaling and spread platelets

A

Platelet Plug

49
Q

The progression of platelet adhesion/signaling

A

Integrin dependent, outside in, inside out

50
Q

These adhesions molecules are structurally similar to immunoglobulins

A

Immunoglobulin like superfamily

51
Q

An examples of immunoglobulin like superfamily, this is expressed when inflammation is in progress to facilitate the transendothelial migration of leukocytes

A

Intracellular adhesion molecule 1 (ICAM-1)

ICAM 2 is another example mentioned in the slide

52
Q

This is a member of the Ig superfamily and is the receptor for HIV-1 in a subclass of lymphocytes known as T cells or helper cells

A

CD4

53
Q

The extracellular segment of a cell adhesion molecule of CAM is folded into two or six immunoglobulin like domains, because of this, CAMs belong to the ______________ of proteins

A

Immunoglobulin superfamily of proteins

54
Q

Ig superfamily molecules can bind to identical molecules on another cell, called…

Or they can bind to other members of the family, called

A
  • trans-*homophilic binding
  • trans*-heterophoilic binding
55
Q

These two immunoglobulin like superfamilies play important roles in T cell interactions and binding of leukocytes to activated or resting endothelial cells

A

ICAM and VCAM (vascular cell adhesion molecule)

56
Q

These two molecules are within tight junctions,

The two molecules belong to this family, because four segments of each protein span the plasma membrane

A

Occludin and Claudin

Tetraspanins

57
Q

Other protein components of tight junctions include…

A

afadin-nectin protein complex

Junctional adhesion molecules (JAMs), zonula occludens (ZO) proteins ZO-1, ZO-2, ZO-3 and F-actin.

58
Q

Tight junctions form a circumferential gasket that contorl the ______ pathway of molecules, or the travel of substances across the epithelium between cells

A

Paracellular pathway of molecules

59
Q

Molecules that travel across the cell follow a ______ pathway

A

Transcellular pathway

60
Q

This part of tight junctions is anchored to ZO-1

A

Afadin nectin complex

61
Q

Nectins form _______ which interact with eachother through the extracellular region

What type of interaction is this?

A
  • cis*-homodimers
  • trans*-homo interaction
62
Q

This part of tight junctions are associated with afadin and ZO-1

How do they interact with one another?

What do they determine about the cell?

A

Junctional adhesion molecules

cis-homodimers

Formation of cell polarity

63
Q

The molecular basic for the formation of tight junction strands seen in freeze-fracture preparations

A

Occludin and Claudins

64
Q

Nectins and JAMs are member of the immunoglobulin superfamily. Their structure is characterized by immunoglobulin loops, each charactized by ______ bonds.

Nectins and JAMs cis-homodimers mediate this type of cell-cell adhesion

A

trans-homo cell-cell adhesion

65
Q

In thin sections, the intercellular space is occluded by these

What is usually found below tight junctions?

A

Occludin, claudins, JAMs, and nectins

Zonula adherens (or belt desmosomes)

66
Q

Different adhesion molecules can act in a coordinated fashion. An example is the rolling and transmigration of _____through the endothelial layer. Selectins, integrins, and ICAMs are all involved

A

Neutrophils

67
Q

Rolling neutrophils in circulation resist shear forces to slow them down along the ____________

A

Vascular endothelium

68
Q

Loose adhesion to the endothelium under conditions of slow flow causethe leukocytes (neutrophils) to roll

Selectins present on the endothelial cell surface bind to __________ __________ on the leukocyte surface

A

Carbohydrate Ligands

Note: carbohydrate containing ligans are on the cell surface, selectins on the endothelium

69
Q

Integrin receptors for _______ and _______ are rapidly activated on the leukocyte surface during rolling

Chemical mediators in the sites of inflammation stimulate the activation of integrins __ and ___

A

endothelial ICAM-1 and ICAM-1 ligands

ß1 and ß2

70
Q

During rolling, these strengthen leukocyte binding to endothelial cell surfaces

A

Integrins

71
Q

Transendothelial migration is mediated by _____ interaction with ligands on endothelial cell surfaces.

______ dynamics participate in this process

A

Integrins

F-actin

72
Q

Neutrophils use a similar mechanism as rolling to escape from blood vessels, primarily _____ _______, into inflammatory sites

A

Post capillary venules

73
Q

Part of how neutrophils escape from blood vessels, primarily postcapillary venules. Leukocytes (neutrophils) establish reversible binding between ________ induced on the endothelial cell surface and ________ on the neutrophil surface. The binding is not strong and it keeps rolling

A

Selectins and carbohydrate ligands

74
Q

2nd step of neutrophils escaping blood vessels, a strong interaction occurs between the neutrophil and the endothelial cell for adhesion. This interaction is mediated in part by _____ on the endothelium and _______

A

ICAM-1 and LFA-1 (lymphocyte function associated antigen 1)

75
Q

3rd step of neutrophils escaping blood vessels, neutrophils migrate across the endothelium along an _______ concentration gradient produced by phagocytic neutrophils

____ contributes to diapedesis by up regulating laminin binding ά6ß1 an ________

Infiltrating neutrophils disrupt the interaction of _____ and ______

A

IL-8

CD99, integrin

JAMs and vascular endothelial cadherins (VE-cadherin)

76
Q

Last step of neutrophils escaping blood vessels, activated macrophages secrete TNF-ά and IL-1 to stimulate the expression of _______ by endothelial cells to keep neutrophils looming

A

selectins

77
Q

Tight Junctions, belt desmosomes, spot desmosomes, and hemidemosomes are called _____ juctions

Gap junctions are called ______, linking adjacent cells.

A

Anchoring Junctions

Communicating junctions

78
Q

The basic unit of a gap junction is the _____, form by 6 ______ molecules surrounding a central channel

A

connexon, connexin

79
Q

In gap junctions, the ________ is an axial channel that allows the direct passage of small signaling molecules between adjacent cells to coordinate cell responses

A

Intercellular channel

80
Q

Clusters of intercellular channels are known as ________ because of the narrow extracellular gap that separates the apposed plasma membranes

A

Gap Junction

81
Q

In gap junctions, six connexin monomers asseemble to form a cylinder with a central open channel, called a…

A

Hexameric connexon

82
Q

In gap junctions, connexons in the plasma membrane of one cell align with connexons of an adjacent cell, forming a _______ intercellular channel connecting the cytoplasm of the apposed cells

A

Hydrophilic

83
Q

A connexin molecule (gap junctions) has how many transmembrane domains?

A

Four

84
Q

The second to last slide is really good for review!

A

DBCS 311 (17 decks)

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