Activation of Caspases || Apoptosis I || 4K Animation

#cellbiology #apoptosis #cancer
Caspase activation during
apoptosis. An initiator caspase contains
a protease domain in its carboxy-terminal
region and a small protein interaction
domain near its amino terminus. It is initially
made in an inactive, monomeric form,
sometimes called procaspase. Apoptotic
signals trigger the assembly of adaptor
proteins carrying multiple binding sites
for the caspase amino-terminal domain.
Upon binding to the adaptor proteins, the
initiator caspases dimerize and are thereby
activated, leading to cleavage of a specific
site in their protease domains. Each
protease domain is then rearranged into
a large and small subunit. In some cases
(not shown), the adaptor-binding domain
of the initiator caspase is also cleaved (see
Figure 18–5). Executioner caspases are
initially formed as inactive dimers. Upon
cleavage at a site in the protease domain
by an initiator caspase, the executioner
caspase dimer undergoes an activating
conformational change. The executioner
caspases then cleave a variety of key
proteins, leading to the controlled death of
the cell.