CAMs Flashcards

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1
Q

list the 2 types of CAMs

A

calcium dependent or independent

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2
Q

list the 4 types of CAMs

A

Ca dep. = cadherins and selectins

Ca indep. = integrins and Ig superfamily

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3
Q

classical cadherins

A
  1. types = E, N, P
  2. homophilic
  3. bind to other cadherins via catenins
  4. actin filaments
  5. adheren junctions
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4
Q

nonclassical cadherins

A
  1. desmocollins and desmogleins
  2. homophilic
  3. intermediate filaments
  4. desmosomes
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5
Q

nonclassical cadherin cytoskeleton associations

A

the desmoplakin, plakoglobin and plakophilin

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6
Q

selectins

A
  1. P, E, L types
  2. heterophilic
  3. actin filaments
  4. bind to carbs
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7
Q

integrins

A
  1. heterophilic
  2. actin filaments
  3. immunological synapses and focal adhesions
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8
Q

hemidesmosomes bind to cytoskeleton components such as ?

A

laminin and fibronectin

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9
Q

classical cadherins are major components in _______ junctions

A

Ca mediated adheren junctions

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10
Q

classical cadherins form ____ and _____ _______ dimers.

A

cis and trans homophilic dimers

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11
Q

E-cadherins

A

epithelial tissues

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12
Q

N-cadherins

A

nervous tissues

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13
Q

P-cadherins

A

placenta tissue

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14
Q

nonclassical cadherins are found in ________ also called ______ .

A

desmosomes

macula adherens

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15
Q

differ between intra and extra cell domains of cadherins

A

interior domain is much more variable than exterior

intra are able to interact w/ different ligands and components to anchor cadherin to cytoskeleon

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16
Q

binding between cadherins is generally ______ .

A

homophilic

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17
Q

cadherin molecules of a specific subtype on one cell bind to other molecules of ________ on adjacent cells.

A

molecules of same kind on adjacent cells

thus the spacing between membranes is precisely defined since they are same molecules w/ same bond lengths

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18
Q

the homophilic binding occurs at the _______ tips of cadherin molecules

A

N-terminal

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19
Q

the protein chains of cadherins form …..

A

terminal knot and nearby pocket

adjacent cadherin binds by inserting it’s knob into the pocket of the other

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20
Q

role of Ca in cadherin-mediated adhesion

A

Ca binds to sites near hinges of each bead so that it is rigid and rod like

if Ca is removed whole thing will be flexible/floppy
causing cadherins to be degraded
bond w/ neighbor cells lost

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21
Q

cadherins bind to their partners w/ _____ affinity.

A

low

thus strong attachments are achieved by many parallel bonds working together

functioning like velcro

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22
Q

cadherin adhesion is _______ but can easily be ______ .

A

group strength is strong

but easily disassembled

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23
Q

cadherin dependent homophilic adhesions mediate highly _____ recognition, thus enabling cells to ?

A

selective
similar cells to stick together and segregate from other types of cells

thus cell “sorting out”

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24
Q

what are the most common type of cadherins?

A

E-cadherins

form dimers via HVA binding face

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25
Q

HVA binding face

A

histidine-valine-alanine seq.

found on E-cadherins, at tip of extra cell end of cadherin molecule

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26
Q

catenin purpose

A

major interface between cadherins and the actin cytoskeleton of the cells being held together

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27
Q

catenin

A

–small proteins that link cytoplasmic end of a cadherin w/ cytoplasmic actin

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28
Q

B and y catenins

A
  • -attach to cytoplasmic end of cadherin

- -b attaches to a catenin

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29
Q

a catenin

A

binds to cytoplasmic actin and b catenin

thus connecting the cadherin to actin cytoskeleton

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30
Q

selectins bind _____, thus belong to the ______ .

A

carbs

lectin group

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31
Q

CRD

A

carb recognition domain of a selectin

carb binding site on extracell end of selectin

32
Q

selectin and Ca

A

Ca binding site located near CRD

Ca is required for selectin binding to carb

33
Q

selectins are involved in ?

A

mvt of leukocytes from blood to tissues

34
Q

types of selectins

A

P – platelets
E – endothelium
L – leukocytes

35
Q

integrins are _____ that are mainly involved in cell - ______ interactions

A

glycoproteins

cell to extracell matrix binding – bind to cytoskeleton and extracell matrix

36
Q

integrins consist of 2 subunits

A
  1. a subunit

2. b subunit

37
Q

integrins bind to _____ and ______ in extracell matrix

A

laminin and fibronectin

38
Q

integrins interact w/ _____ sequence

A

RGD – arginine-glycine-aspartic acid

seq. in laminin-fibronectin

39
Q

laminin and fibronectin are associated w/

A

type IV collagen
GAGs
entactin

40
Q

in ________, integrins link the _____ of cells to the ______ . via ?

A

hemidesmosomes
basal domain to extracell matrix

via tonofilaments such as keratin

41
Q

immunoglobulin superfamily types

A

N-CAM
I-CAM1
I-CAM2

42
Q

N-CAM

A

neural adhesion molecules

mediate both homo- and heterophilic interactions

43
Q

I-CAM1 AND 2

A

facilitate transendothelial migration

44
Q

categories of junctional complexes

A
  1. adherens
  2. occludens
  3. gap junctions
45
Q

types of junctions

A
  1. zonula – belt like-adheren and occluden

2. macula – spot adhesion

46
Q

zonula are associated w/ _______ and macula are associated w/ _______ .

A

intracell actin

intracell tonofilaments

47
Q

adherens are anchoring junctions characterized by intercellular spaces _______ .

A

filled w/ cadherin proteins - desmogleins and desmocollins

48
Q

cadherin proteins are anchored to ________ containing _____ ?

A

cytoplasmic plaques

desmoplakin and plakoglobin

49
Q

cadherin located related to whole cell

A

on lateral domains

just below apical domains

50
Q

desmosomes are similar to adheren junctions but link to ?

A

intermediate filaments

51
Q

desmosomes provide ____ strength

A

mechanical strength

structural framework of great tensile strength

52
Q

structure of desmosome

A

cytoplasmic plaque w/ intermediate filaments attached to it

53
Q

hemidesmosomes

A

anchoring junctions than attach the basal domain of epithelial cells to the basal lamina

54
Q

hemidesmosome structure

A
  1. cytoplasmic plate – intermediate filaments

2. membrane plaque

55
Q

hemidesmosome binding

A

a membrane plaque links to the basal lamina via anchoring filaments and integrins

56
Q

claudens and occludins

A

transmembrane proteins associated w/ zonula occludens

responsible for occlusive properties of the tight junctions

57
Q

tight junctions seal …..

A

seal gaps between epithelial cells on basolateral side near apical domain

58
Q

gap junctions allow …..

A

the passage of small water-soluble molecules from cell to cell

located on basolateral side near basal domain

59
Q

why do we need tight junctions?

A

to block the backflow of nutrient molecules in-between epithelial cells

especially import in digestive system

60
Q

_____ is the main transmembrane protein in tight junctions

A

claudin

61
Q

________ is the second major transmembrane protein in tight junctions and it’s purpose is _____ .

A

occludins

unknown

62
Q

JAM

A

junctional adhesion molecules

63
Q

JAMs include ?

A

tight junctions
adheren junctions
desmosomes

64
Q

list 3 main functions of tight junctions

A
  1. barriers
  2. fence function – limit lateral diffusion
  3. signaling function – magnetic bar attracting various proteins
65
Q

to fully polarize, epithelial cells must …..

A

separate the apical and basolateral surfaces via tight junctions

66
Q

3 conserved polarity protein complexes that control polarization processes

A
  1. par
  2. crumbs
  3. scribble
67
Q

gap junctions

A

communicating junction that allows cells to directly communicate

68
Q

gap junctions are composed of ______

A

connexons

connexons are 6 connexins in a hollow hexagon structure

69
Q

gap junctions in electrically coupled nerve cells allow …..

A

action potentials to spread rapidly from cell to cell w/o the delay that chemical synapses have

70
Q

if a cell becomes damaged it will experience a large influx of Ca ions, what is the result to gap junctions

A

it’s gap junctions will immediately close so that it’s neighbor cells will not become damaged too

71
Q

what is responsible for reducing gap junction communication between neurons

A

dopamine

72
Q

purpose of BM

A

the basement membrane separates epithelial layers from the CT support underneath

73
Q

list the 5 components of the BM

A
  1. laminin
  2. fibronectin
  3. type IV collagen
  4. GAGs
  5. entactin
74
Q

type IV collagen is produced by ?

A

epithelial cells

does not create long fibrils like collagen I and II

75
Q

laminin binding sites

A
  1. integrins
  2. type IV collagen
  3. entactin
  4. heparan sulfate
76
Q

forms of fibronectin

A

cellular and plasma form

77
Q

fibronectin binding sites

A
  1. integrins
  2. collagen
  3. fibrin
  4. heparan sulfate = heparin