The spontaneous aggregation of soluble proteins and the
generation of amyloid fibers poses great challenges to the biomedical sciences,for being the source of serious human degenerative disorders. We need to consider models for understanding the molecular basis and biological significance of the formation of such aggregates.

 
It has been recently observed that these proteins are not related to human diseases can be added in vitro, forming complexes with structural and cytotoxic properties indistinguishable from those associated with pathological conditions indicated. Such is the case of the SH3 domain (SRC homology with type 3) of the p58 subunit of PI3-SH3 (phosphatidylinositol-3 kinase), one of the best characterized examples of small globular protein unrelated to any known pathological condition and that can form amyloid fibrils in vitro. This example
led the authors of this work, in collaboration with several European enters, to consider whether the protein aggregates that underlie these disorders may exhibit similar toxicity mechanisms, and if it has some evolutionary significance.

Have studied the behavior of a homologous protein to PI3-SH3,-spectrin SH3, without the ability to form amyloid fibers. The inclusion in it of a short sequence of six amino acds, from PI3-SH3, creates an amyloidogenic protein similar in behavior to the original PI3-SH3.These results provide clues to the authors that short sequences may mediate or facilitate the incorporation of globular proteins into amyloid structures.