  Filament formation by non-cytoskeletal enzymes has been known for decades,
yet only relatively recently has its wide-spread role in enzyme regulation and
biology come to be appreciated. This comprehensive review summarizes what is
known for each enzyme confirmed to form filamentous structures in vitro, and
for the many that are known only to form large self-assemblies within cells.
For some enzymes, studies describing both the in vitro filamentous structures
and cellular self-assembly formation are also known and described. Special
attention is paid to the detailed structures of each type of enzyme filament,
as well as the roles the structures play in enzyme regulation and in biology.
Where it is known or hypothesized, the advantages conferred by enzyme
filamentation are reviewed. Finally, the similarities, differences, and
comparison to the SgrAI system are also highlighted.
