Bioinformatics Education Dissemination: Reaching Out, Connecting and Knitting-together

TRP Cage Problem Space

Trpcage (sequence NLYIQWLKDGGPSSGRPPPS) is one of the smallest mini-proteins ( PDB ID = 1L2Y ) known to date and exhibits stable, spontaneous, two-state folding properties. The folding appears to be cooperative and based on the hydrophobic effect of a Tryptophan side chain that is surrounded by Proline rings. This 20-residue mini-protein is a truncated and optimized version of the predominantly helical, 39-residue peptide exendin-4 (EX4) from Gila monster saliva.

Read an article about the summer workshop during which this Trpcage model was built.

The Trpcage itself is comprised of the close association of Gly-11, and three Pro residues –12, 18, and 19–with the two aromatic side chains Tyr-3 and Trp-6. The indole ring of Trp-6 forms the center of a hydrophobic core, bordered by the side chains of Tyr-3, Leu-7, and two extra-helical non-neighboring Prolines (12 and 18). Residues 2-8 form a short a-helix; residues 11-14 form a 310-helix. The Proline triplet reveals a polyproline II helix at the C-terminus, with the central Pro-18 forming part of the cage.

Physical models were generated by Tia Johnson and Rama Viswanathan (Beloit College) during the Summer Modeling Institute 2003. Follow the "molecules" link to the left to explore these models.

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