Proteins IV

Question 1

Most play structural or mechanical role and tend to form elongated structures of high regularity and is found primarily in skin, bone and cartilage

Answer 1

Fibrous proteins

Question 2

Abundant in ligaments, lungs, walls of arteries and skin. It lacks regular secondary structure and it forms crosslinks involving allysine residues.

Answer 2

Elastin:

Question 3

Exists as dimers of right handed α-helix chains that run in parallel and coil around each other in a left-handed supertwist (coiled-coil).

Answer 3

α-Keratin and tropomyosin

Question 4

An extracellular protein secreted from fibroblasts and serves as a matrix material to provide strength and pliability to tissues

Answer 4

Collagen

It has a triple helix structure (similar to polyproline type 2 helix) that is made of three polypeptides

Question 5

caused by faulty synthesis or structure of collagen; as a result, joints have a tendency to dislocate or subluxate

Answer 5

Ehlers-Danlos syndrome (EDS)

Question 6

Skin forms cigarette like scars and skin is highly elastic, velvety and bruises and tears easily. As a result, skin is very difficult to heal. Caused by mutation in type V collagen.

Answer 6

Classic EDS

Question 7

Most serious type because it can lead to premature death, yet most rare type; associated with type 3 collagen mutation that causes rupture of blood vessels and/or organs, thin and translucent skin and extensive bruising.

Answer 7

Vascular EDS

Question 8

Caused by a mutation in type 1 collagen which leads to loose and unstable joints; as well as stretchy, fragile skin.

Answer 8

Arthrochalasia

Question 9

Due to a mutation in lysyl hydroxylase gene, which causes an abnormally curved spine

Answer 9

Kyphoscoliosis

Question 10

(brittle bone disease) is an autosomal dominant gene disorder due to a deficiency in type 1 collagen which may be a result of a point mutation within the alpha 1 chain

Answer 10

Osteogenesis imperfecta

Question 11

is an autoimmune disorder in which there is hypersensitivity to antigens present in the non-collagenous domain of the α3 chain of type 4 collagen in the glomerulus(kidney) and pulmonary alveolus. The immune system wrongly recognizes the antigens and produces antibodies towards them.

Answer 11

Goodpasture’s Syndrome

Question 12

Caused by a dietary deficiency of vitamin C, but has similar symptoms of a collagen mutation disorder such as poor bone growth, poor wound healing, severe bruising and also bleeding gums and loose teeth.

Answer 12

Scurvy

Question 13

(triple helix) is the basic functional unit of all types of collagen. The triple helix is right-handed, but each polypeptide chain is left-handed and run parallel. Hydrophobic forces and H-bonding between Gly amino group and carbonyl groups of other residues stabilize the molecule.

Answer 13

Tropocollagen

Question 14

Involves tropocollagen being organized into bundles called fibrils

Answer 14

Cross-linking

Question 15

o Type 1 Collagen molecules form structured arrays (fibers) on outer surface of

Answer 15

fibroblasts

Question 16

found in the basal lamina of intestinal epithelial cells. In the basal lamina, layer includes: Laminin, Perlecan and Nidogen/Enactin to form a “mesh work”.

Answer 16

Type 4 collagen