Regulation of Pathways

Pictures of the Thromboplastin - factor VIIa complex

As noted a couple of pages ago, Thromboplastin along with some phosphatydl- lipid vessicles is released from damaged cells to begin the blood clotting cascade. In the pictures below Atoms are colored according to polarity:

• green = polar amino acid side chains
• red = hydrophobic (nonpolar) amino acid side chains

There are three polypeptides in the picture

1. Factor VIIa heavy chain (contains the active site)
   which can be seen in SOME view but not all
   • SER195 = purple
   • HIS 57 = white
   • Asp 102 = yellow
2. Factor VIIa Light chain (contains the γ-carboxyglutamates that are necessary for bind calcium -- not shown in this set of pictures because the data is not present this time)
3. Thromboplastin. (the atoms for this polypeptide can be "turned off" to see this peptide in "ribbon representation")

Look for regions of hydrophobic amino acid dominance near the interface between the Factor VIIa light chain and Thromboplastin. Notice that the "hydrophobic patch" is much larger in the complete complex than in factor VII alone.

All three components in ribbon representation: Thromboplastin - green; Light chain - purple; Heavy Chain - red; notice how the light chain is wrapped around thromboplastin. The active site amino acids are shown as spheres near the top./b>
	ribbon representation Thromb. only in ribbon ALL atoms Rotate to active site Active site. Thromb in ribbon