motifs Flashcards
what are motifs
Particular arrangements of 2° structures (super-secondary structures) that occur frequently within a polypeptide and can be associated with a specific biological function
list all motifs
- Helix-loop-helix motif
- Hairpin Beta motif
- Greek key motif
- Beta-α-Beta motif
- Coiled coil motif
- Zinc finger motif
- Beta barrel motif
give examples of Helix-loop-helix Motif
DNA binding motif
Calcium binding Motifs
what is Hairpin beta motif
Two adjacent anti-parallel beta strands joined by a hairpin loop
give example of hairpin beta motif
Trypsin inhibitor
sea snake venom- erabutoxin
what is Greek Key Motif
The most common way to connect 4 adjacent anti-parallel beta strands
give an example of Geek key Motif
nuclease enzyme(bacterial)
what is Beta-α-Beta Motif
α-Helix connects 2 parallel Beta strands
Beta-α-Beta motif found in almost all proteins that contain a parallel Beta sheet
what is Coiled Coil Motif
• Hydrophobic R-groups of α-helices assemble together to form a coiled coil
give an example of Coiled Coil Motif
Leucine zipper
what is a Zinc Finger
- Two anti-parallel Beta-sheets followed by an α-helix, stabilised by a zinc ion
- Common motif in transcription factors
- Can be present frequently within the same polypeptide chain
what is Beta Barrel Motif
• Multiple anti-parallel Beta-sheets linked together in:
- Greek key motifs
- Up and down sheets
- Jelly rolls (complex)
- Pore-forming
- Water channels (aquaporins)
what are Domains?
- A polypeptide chain (or part of chain) that folds independently into a stable structure with its own hydrophobic core
- Formed from several simple motifs and additional secondary structure elements
- Proteins can have anything from one to several tens of domains
- Each domain is associated with a distinct biological function
