Pre or Pro Protein/Domain

Cited from Re: What is the function of a protein's prodomain? Why are they called that?

"pre-" was adopted as the prefix that means "before N-terminal cleavage during a secretion event".

Many proteins require additional proteolytic processing to become fully functional. This also involves cleavage of a peptide from the N-terminus, but is not part of the secretory process. So the prefix "pro-" was adopted to describe the protein prior to this processing event.

"preproprotein" (the N-terminal is cleaved during secretion, then cleaved again to make the protein active).

Caspase is a good example. It is synthesised as an inactive proprotein. In this case the term "prodomain" is used, because the N-terminal region is folded into a discrete structural unit with a specific function (the definition of a domain). Usually the prodomain mediates interaction with other proteins in a complex. Proteolytic cleavage then removes the prodomain, activates the caspase and triggers a cascade in which caspases activate other caspases, leading eventually to the cleavage of key target proteins (caspase substrates) and cell death. Other proteins besides caspases also contain prodomains that mediate a particular process for the protein.