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Unformatted text preview: of apoptosis In mammalian cells,
many cell death signals induce apoptosis as a result of damage to mitochondria
(the intrinsic pathway of apoptosis). When active, the proapoptotic multidomain
Bcl-2 family proteins (Bak and Bax) form oligomers in the outer membrane of mitochondria, resulting in the release of cytochrome c from the intermembrane space.
Release of cytochrome c leads to the formation of apoptosomes containing Apaf-1
and caspase-9 in which caspase-9 is activated. Caspase-9 then activates downstream caspases, such as caspase-3, by proteolytic cleavage. 9 Death
signal Bax chondria by Bax or Bak results not only in the release of cytochrome c but
also of IAP inhibitors that may help to stimulate caspase activity. Signaling Pathways that Regulate Apoptosis
Programmed cell death is regulated by the integrated activity of a variety of
signaling pathways, some acting to induce cell death and others acting to
promote cell survival. These signals control the fate of individual cells, so
that cell survival or elimination is determined by the needs of the organism
as a whole. The pathways that induce apoptos...
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