  Intrinsically Disordered Proteins (IDPs) perform a broad range of biological
functions. Their relevance has motivated intense research activity seeking to
characterize their sequence/structure/function relationships. However, the
conformational plasticity of these molecules hampers the application of
traditional structural approaches, and new tools and concepts are being
developed to address the challenges they pose. Small-Angle Scattering (SAS) is
a structural biology technique that probes the size and shape of disordered
proteins and their complexes with other biomolecules. The low-resolution nature
of SAS can be compensated with specially designed computational tools and its
combined interpretation with complementary structural information. In this
review, we describe recent advances in the application of SAS to disordered
proteins and highly flexible complexes and discuss current challenges.
