MY FAVORITE PROTEIN: Leptin

3D Structure of Leptin

CPK Color Scheme C O N P S

A chime tutorial for the protein Leptin.

For more information about leptin please visit my previous webpages: Leptin and Leptin Orthologs

Click here to reset the view of Leptin

Leptin consists of 4 alpha helices. These helices are color coded as follows: helix A is blue, helix B is green, helix C is red, and helix D is yellow. . The N and C termini are labeled.

Notice the disufide bridge that helps in protein folding (highlighted in yellow). . This disulfide bridge keeps the C terminal end (Cysteine on the right) folded in towards the CD loop (Cysteine on the left). A mutation of either cysteine causes the molecule to fold incorrectly and the protein is then inactive (Zhang, et al).

Click here to see the hydrophobic residues in Leptin. . The wireframe structures are the hydrophobic residues and the rest of the molecule is displayed in backbone format. Several amino acids are labeled. It can be seen from this image that the hydrophobic residues tend to lie on the inside of the molecule between the helical structures.

Click here to see a possible binding site on leptin. Although the exact binding site is unknown, the area highlighted in red is a suspected binding site. This area (AB loop) is highly flexible and this flexibility would allow for ligand binding (Zhang, et al).

These last 5 residues in helix D are important in maintaining the structure of leptin.

Zhang, et al states, "disulphide formation and the subsequent kinked D helix structure are important for structure folding and receptor binding."

All of the features described above place leptin in the family of other long-chain helical cytokines (Zhang, et al).

References:

Zhang, F. et al. Crystal Structure of the obese protein leptin-E100. Nature 387, 206-2094 (1997).

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