In mammalian cells members of the bcl 2 family act at

Info iconThis preview shows page 1. Sign up to view the full content.

View Full Document Right Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: s of the Bcl-2 family act at mitochondria, which play a central role in controlling programmed cell death ( Figure 17.8). When activated, Bax and Bak form oligomers in the mitochondrial outer membrane. Formation of these Bax or Bak oligomers leads to the release of cytochrome c f rom the mitochondrial intermembrane space, either by forming pores or by interacting with other mitochondrial outer membrane proteins. The release of cytochrome c from mitochondria then triggers caspase activation. In particular, the key initiator caspase in mammalian cells (caspase-9) is activated by forming a complex with Apaf-1 in the apoptosome. In mammals, formation of this complex also requires cytochrome c. Under normal conditions of cell survival, cytochrome c is localized to the mitochondrial intermembrane space (see Figure 11.10) while Apaf-1 and caspase-9 are found in the cytosol, so caspase-9 remains inactive. Activation of Bax or Bak results in the release of cytochrome c to the cytosol, where it binds to Apaf-1 and triggers apoptosome formation and caspase-9 activation. Caspases are also regulated...
View Full Document

This note was uploaded on 08/25/2009 for the course BIO 315 taught by Professor Steiner during the Spring '08 term at Kentucky.

Ask a homework question - tutors are online