Lecture 4: Protein Motifs & Domains

Question 1

Domain

Answer 1

• Made up of motifs
• [Part of a] Polypeptide chain that can fold independently into stable teritary

Question 2

Motif

Answer 2

Simple combinations of a few secondary structure elements w a specific geometric arrangement

Question 3

Hairpin ϐ motif

Answer 3

• 2 strands connected by a loop
• Anti-parallel
• Length of loop regions vary generally bw 2-5 residues
• Forms stable building block for larger structures

Question 4

Greek key

Answer 4

• 4 beta sheets
• Arranged in anti-parallel arrangement

Question 5

β—α—β motif

Answer 5

• Beta sheets separated by alpha helix
• Parallel
• Short loop between the 2 strands, usually alpha helix

Question 6

Ig Domain

Answer 6

• 7 anti-parallel beta sheets
• Disulfide bonds which link the different sides together
• Found in proteins involved in ligand binding

Question 7

IgG

Answer 7

• Heavy chain n light chains connected together by disulfide bonds
• Each n every polypeptide chains consist of a number of domains which are connected together
• Carbohydrate molecule which are attached due to a post-translational modification

Question 8

How does the arrangement of IGG gene structures contribute to the generation of diverse proteins for binding various antigens?

Answer 8

Can be spliced different bits of the genes together to gv different bits of proteins that give the variation required for binding various different antigens

Question 9

Alpha helices are versatile to produce many different structural motifs

Answer 9

• Membrane spanning domains
• Structural n motile proteins
• Fibrous proteins in skin, hair, feathers