Cell Junctions, Adehsion Molecules And EC Matrix

Question 1

Characteristics of Selectins

Answer 1

• Ca+ Dependent Adhesion molecule
• Bind to Carbs
• Belong to the Lectin group

Question 2

Types of Junctions

Answer 2

1. Zonula
   - Travel around CIRCUMFERENCE of the cell
   - Link neighboring cells to the central cell
2. Macula
   - Associated with HEMI/DESMOSOMES

Question 3

Another name for Zonula Occludens

Answer 3

Tight Junctions

Question 4

Components of the Basement Membrane

Answer 4

1. Basal Lamina
   - Produced by Epithelium
2. Reticular Lamina
   - Produced by Connective tissue

Question 5

Sub Categories of Cadherins. Where are they found?

Answer 5

1. E-Cad
   - Found in EPITHELIAL tissue (Most common)
2. N-Cad
   - Found in NERVE cells
3. P-Cad
   - Found in Placenta

Question 6

What are Hemidesmosomes?

Answer 6

Anchoring Jxns that anchor the Basal Domain of the Epithelial cell to Basal Lamina

Question 7

Composition of Gap Jxns

Answer 7

• Composed of ConnexOns

- 1 ConnexOn = 6 ConnexIn, forming a hexagonal structure

Question 8

EC Integrins bind to what?

Answer 8

Molecules in the ECM

• Such ad Fibronectin and Laminin

Question 9

Role of Integrins in Hemi-Desmosomes

Answer 9

Integrins link the basal domains of cells to the EC Matrix via IC Tonofilaments

Question 10

Characteristics of Non-Classical Cadherins

Answer 10

• Found in DESMOSOMES
• Include
  1. Desmocollins
  2. Desmogleins

Question 11

Purpose of Catenins

Answer 11

Serve as a Major interface b/w the Cadherins that hold ADJACENT cells together AND the ACTIN cytoskeleton of those cells

Question 12

What 2 groups are Cell Adhesion Molecules divided into?

Answer 12

1. Calcium Dependent

2. Calcium INDEPENDENT

Question 13

Main Fxn of Selectins

Answer 13

Involved in the movement of Leukocytes from blood to tissue

Question 14

What are Integrins? Where do they bind?

Answer 14

• Glycoproteins that are involved in Cell EC Matrix Interactions
• They bind to BOTH EC Matrix and the CYTOSKELETON

Question 15

Fxn of the basement Membrane

Answer 15

Separates the Epithelial layer from its Connective tissue

Question 16

Diff B/w Focal Adhesion and Desmosomes

Answer 16

FA
- IC attachment is ACTIN

Desmosome
- IC attachment is KERATIN
(Tonofilaments)

Question 17

Sub Categories of SELECTINS. What are they associated with?

Answer 17

1. P-Sel
   - Associated with Platelets
2. E-Sel
   - Associated w/ activated Endothelial cells
3. L-Sel
   - Associated with Leukocytes

Question 18

Zonula Adherens are associated with ____ while the Macula Adherens are associated with the _____.

Answer 18

1. Actin Microfilaments

2. Intermediate Filaments

Question 19

Members of the IG Superfamily

Answer 19

1. N-CAM
   - Neural Cell Adhesion Molecules
   - Mediate Both Homophilic and Heterophiic Interactions
2. I-CAM
   - IC Cell Adhesion Molecule
   - Facilitates the trans Endothelial migration of Leukocytes

Question 20

Characteristics of Classical Cadherins

Answer 20

• Major component in Ca2+ mediated ADHEREN Jxn

- Typically form a CIS and TRANS Homophilic dimers

Question 21

Fxns of Gap Jxns

Answer 21

• Close when [Ca2+] are High

- Responsible for Chemical and Electrical coupling

Question 22

IG Superfamily Characteristics

Answer 22

Possess an EC Segment w/ 1+ Folded domains

• Characteristic of IG

Question 23

Categories of Junctional Complexes

Answer 23

1. Adherens
2. Occludens
3. Gap Jxns

Question 24

Fxn of Occludens

Answer 24

• Establish an IMPERMEABLE Barrier b/w adjacent cells

- Prevent Paracellular Transport

Question 25

Ca2+ Independent molecules

Answer 25

- Integrins | - Immunoglobulin Superfamily Molecules

Question 26

Consequence of loss of E-Cadherins

Answer 26

Associated with Invasive behavior of TUMOR Cells

Question 27

Characteristics of Laminin

Answer 27

- The MAJOR component of the Basal Lamina | - Has binding sites for Integrins, Type 4 collagen and PTG

Question 28

Fxn of Tight Jxns

Answer 28

Provide a Barrier against the Paracellular Transport pathway

Question 29

Integrins interact it’s with what sequence of Fibronectin

Answer 29

RGD - > Arg-Gly-Asp

Question 30

*Properties of Type 4 Collagen*

Answer 30

Predominant collagen in the BASEMENT MEMBRANE | Noncellular layer that epithelia cells rest on

Question 31

Where do Alpha Catenins bind?

Answer 31

Directly to the Cytoplasmic Actin

Question 32

Fxn of Adherens

Answer 32

- ANCHOR cells together - Reinforce integrity of tissue - Found on the Basolateral surface of Epithelial cells

Question 33

Ca2+ Dependent molecules

Answer 33

- Cadherins | - Selectin

Question 34

Fxn of Gap Jxns

Answer 34

- Molecular Pores that enable cells to rapidly exchange ions - Help coordinate activities