Extracellular Matrix

Question 1

Components of ECM (4)

Answer 1

Structural proteins
Glycosaminoglycans (GAG)
Proteoglycans
Adhesive glycoproteins

Question 2

GAG’s (3 examples)

Answer 2

Inflexible

Includes: hyaluronic acid, chondroitin sulfate, heparan sulfate

Question 3

Hyaluronic acid is NOT

Answer 3

Sulfate on amino sugar

Question 4

Proteoglycans

Answer 4

When GAG is coupled to a core protein

Found in cartilage “aggregation”

Question 5

Heparan Sulfate Proteoglycans

Answer 5

Membrane associated - syndecans

Extracellular = perlecans

Question 6

Elastin

Answer 6

Allow stretching and recoil of CT

Assembled extracellularly

Question 7

Marfan Syndrome

Answer 7

Misense in gene coding fibrillin I
Increase length of appendages
Aorta prone to rupture due to lack of recoil

Question 8

Collagen

Answer 8

Strength (3 alpha chains wrap around each other)

Repeating Gly- X- Y structure

Question 9

Type 1 Collagen

Answer 9

Bones, tendons

Mutation - osteogenesis imperfecta (brittle bones)

Question 10

Type 3 Collagen

Answer 10

Skin, blood vessels

Mutation - hyper extendable skin

Question 11

Type 9 Collagen

Answer 11

Cartilage
Outside type 2
“Hinge”, joint integrity
Mutation - arthritis

Question 12

Type 4 Collagen

Answer 12

Network forming collagen (chicken wire array)
Basal lamina
Basement membrane

Question 13

Type 7 Collagen

Answer 13

Anchoring fibrils at epithelial-CT junctions
Use C-termini disulfide bonds
Mutation - epidermolysis bullosa (epithelium and basement membrane peeled away)

Question 14

Type XVII Collagen

Answer 14

Connect basement membrane to epithelium
Use anchoring filaments
Transmembrane protein

Question 15

Fibronectin

Answer 15

2 subunits connected by disulfide bridges

Bind to other ECM molecules and integrins with RGD sequence

Question 16

Laminin

Answer 16

Modular domain promotes adhesion

Question 17

Integrins

Answer 17

Dimer of alpha/beta

beta subunit binds cytoskeleton (typically actin)

Question 18

Integrins mediate ________

Answer 18

Communication between ECM and internal cell signaling

Extra and intra cellular signals

Question 19

B1 subunit

Answer 19

Fibronectin and Lamin

Question 20

B2 subunit

Answer 20

WBC

Question 21

Leukocyte Adhesion Deficiency

Answer 21

WBC can’t bind endothelium

Mutation in B2 subunit

Question 22

B3 subunit

Answer 22

Platelets

Question 23

Glanzmann’s

Answer 23

Fibrin doesn’t bind during clotting

Mutation in B3 subunit

Question 24

B4 subunit

Answer 24

Hemidesmosomes

Question 25

Integrin steps (4)

Answer 25

1. Integrins cluster after binding substrate Need RGD sequence
2. Organize cytoskeleton by binding actin and actin-binding proteins
3. Focal adhesions form
4. Recruit signaling molecules