Posts Tagged Protein

Anastasia and Thomas’s Investigation of Prion Structural Simularities in Rabbits (3O79), Mice and Humans

Prions are a destructive family of proteins, due to a transformational (mis-folding) of a alpha helix to a beta sheet. The beta sheets only represent 3% of the proteins secondary structure (Fig. 1) This minor change in protein conformation is enough to turn a useful protein into a highly destructive stable force.



Figure 1. 56% helical (5 helices; 59 residues) 3% beta sheet (2 strands; 4 residues) of 3070 rabbit prion

Its amino acid sequence (95% match in sheep) as well as its 3-D structure ( 97% similarity to humans) is highly conserved through different species. What makes misfolding such a problem is its ability to perpetuate misfolding of the surrounding proteins. It has been found that rabbits have a helix capping motif the dramatically lowers the propensity of prion formation (Fig. 2)

mouse

rabbit

Figure 2: Mouse vs Rabbit 3-D cartoon structure using Pymol

In conclusion prions have a highly conserved structure that is both minor yet destructive.

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Protein visualization (Rachel / Thomas)

Solved crystal structure of BRCA1 BRCT (made in Jmol):

Electrostatic map of BRCA1 BRCT (made in Pymol):

Sequence of BRCA1 BRCT showing features such as beta strands and alpha helices:

The structure has a diameter of ~27 A.  ~55 A in length.

There are a variety of secondary structures including beta turns, beta strands and alpha helices.

BRCA1 is composed of 215 residues.

Conserf run (MSA):

Dark purple regions are conserved.  Notice ligands binding in that region.

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