Lecture 2

Question 0

Basal Lamina Components

Answer 0

• Laminin
• Type IV collagen
• Entactin (nidogen) attached to laminin and collagen
• Proteoglycans

Question 1

Basement Membrane 2 components

Answer 1

• basal lamina, produced by epithelium

- reticular lamina, connective tissue

Question 2

Laminin

Answer 2

• Major component of BL
• 3 chains: alpha, beta, gamma
• binding sites for integrins, type IV, entactin, and proteoglycans

Question 3

Type IV collagen

Answer 3

• doesn’t form fibrils like type I

- prodcued by epithelial cell, unlike type I which is secreted by fibroblast

Question 4

Fibronectin

Answer 4

• protein made up of two polypeptide chains cross-linked by disulfide bonds
• Cellular, produced by fibroblasts, part of extracellular matrix
• Plasma, secreted into bloodstream by hepatocytes

Question 5

Fibronectin binding sites

Answer 5

• can bind to themselves and others, forming EM support chain
• Heparin (proteoglycan)
• Integrins
• Collagen
• Fibrin

Question 6

Calcium Dependent CAMs

Answer 6

• cadherins

- selectins

Question 7

Calcium Independent CAMs

Answer 7

• integrins

- Immunoglobulin superfamily molecules

Question 8

Classical Cadherins

Answer 8

• major components in Ca mediated adherens junctions
• cis/trans homophilic dimers
• E-N-P-cadherins

Question 9

Nonclassical Cadherins

Answer 9

• desmocollins and desmogleins

- found in desmosomes (macula adherens)

Question 10

Homophilic Dimers

Answer 10

• two similar molecules that bind together
• cis, two identical bin from same cell
• trans, two identical from different cells bind

Question 11

E-cadherins

Answer 11

• found in epithelial tissue, most common
• adhere to one another
• HVA binding face
• loss associated with invasive behavior of tumors

Question 12

N-cadherins

Answer 12

-found in nerve cells

Question 13

P-cadherins

Answer 13

-found in the placenta

Question 14

HVA binding face

Answer 14

• histidine-valine-alanine sequence
• found at tip of extracellular end of cadherin
• facilitates formation of trans-homophilic (lets one bind to another)
• Ca binds to four extracellular domains to facilitate cis

Question 15

Catenins

Answer 15

• small proteins that link cytoplasmic end of cadherin with actin
• three forms alpha, beta, gamma
• serve as major interface between cadherins that hold adjacent cells together and the actin cyto of those cells

Question 16

Beta and Gamma catenins

Answer 16

• plakoglobin catenins
• attach to cytoplasmic end of a cadherin
• beta also serve as transcription cofactor
• beta attached to alpha catenin

Question 17

Alpha Catenin

Answer 17

-binds directly to cytoplasmic actin

Question 18

Selectins

Answer 18

• bind to carbs, belong to lectin
• bind on carbohydrate-recognition domain (CRD)
• Ca required to bind on CRD
• involved in movement of leukocytes (blood cells) to tissues (extravasation)

Question 19

Classes of Selectins

Answer 19

• P-selectins: platelets
• E-selectins: activated endothelial cells
• L-selectins: leukocytes

Question 20

Integrins

Answer 20

• glycoproteins involved in cell-extracellular matrix interactions
• bind to both EM and cytoplasm
• two subunits, one alpha (17 kinds) one beta (8 kinds)
• extracellular domains bind to fibronectin, laminin
• interact with RGD (arg-gly-asp)

Question 21

Connecting Proteins

Answer 21

-talin, vinculin, alpha-actinin

Question 22

Tonofilaments

Answer 22

• in hemidesmosomes, integrins link basal domains via intracellural tono
• resist tension

Question 23

Immunogobulin Superfamily

Answer 23

• possess an extracellular segment with 1 or more folded domains
• N-CAM: neural adhesion molecules, mediate homo and heterophilic interactions
• I-CAM-1, I-CAM-2: facilitate transendothelial mmigration of leukcytes

Question 24

Adherens

Answer 24

• Junctional complex, anchor cells together and reinforce integrity
• found on basolateral surfaces of epithelial cells

Question 25

Occludens

Answer 25

• junctional complex, establish an impermeable barrier etween cells
• prevent paracellular transport

Question 26

Gap Junctions

Answer 26

• composed of molecular pores, enable cells to rapidly exchange ions
• can shut down if injured

Question 27

Zonula

Answer 27

• tight junction, can be adherens or occludens
• travel around cell and link neighboring cells
• belt-lie complexes
• associated with intracellular actin

Question 28

Macula

Answer 28

• spot or snap-like junction
• adherens, desmosomes or hemi
• intracellular intermediates (tonofilaments)

Question 29

Adherens

Answer 29

• anchoring junctions characterized by intercellular spaces
• spaces filled with cadherin protiens
• desmogleins, desmocollins
• cadherin proteins anchored to cyto plaques containing desmopakin, plakoglobin

Question 30

Desmogleins

Answer 30

• 1 & 2 found in epidermis

- autoantibodies to 1 result in pemphigus foiaceus

Question 31

Heidesmosomes

Answer 31

• anchor basal domain of epithelial to basal lamina
• cyto pate w/ intermediate filaments lie keratin
• membrane plaque linking hemi to basa via laminin 5 and integrins

Question 32

Zonula Occludens

Answer 32

• JAMs and Nectin, both Ig family
• nectin intracellular molecule, afadin
• JAMs intracellularly with both afadin and ZO-1

Question 33

Focal Adhesions

Answer 33

• spots that anchor the cell to EM via integrins

- intracellular attachment to actin filaments via connecting proteins

Question 34

Gap Junctions

Answer 34

• communicating junctions
• composed of connexons, each with 6 connexins, forming hexagonal structure with hollow center
• facilitate movement of molecules
• often clustered into patches