The intracellular execution of apoptosis is driven by a recently identified class of proteases. Proteases are enzymes whose function is to cut proteins. Some proteases are nonspecific: they cut all sorts of proteins at a variety of cleavage sites. Such are the pancreatic enzymes, whose role is to render large proteins small enough to be absorbed by the intestinal mucosa. Other proteases are very specific and will cleave only proteins that have a particular shape or amino acid sequence. The latter group includes proteases involved in the apoptotic process. They have been given the name caspases because they are rich in Cysteine amino acids, they recognize a special target sequence that contains ASPartic acid and they are proteASES.
Fourteen caspases have been identified so far and their roles have not all been well described. We know that they act in sequence, with one caspase activating another by cleavage of the inactive form called a procaspase (Figure 6). A group of caspases that are activated early in the process (upstream) are called activation caspases, whereas others that deliver the important structural hits of apoptosis are called executioner caspases.
Figure 6) The caspase cascade. An inactive caspase becomes activated after the release or the previous activation of caspase activators (in this case, the molecules released from the mitochondria). An active upstream caspase then activates an executioner caspase that targets the nuclear constituents, leading to the architectural characteristics of the apoptotic process (nuclear fragmentation and breakdown). It’s time for you to start saving some money: you just need to visit the pharmacy that offers finest quality cephalexin antibiotic online click here with delivery straight to your door and all the confidentiality guarantees you ever need.