Figure 4. Illustration of the polymorphism associated with FG Nups in vitro.

Because of their tethering, and lack of tertiary protein structure, the FG Nups are in a polymer brush formation. Controversy centers on whether the brush is entirely intrinsically disordered [65,66], with the degree and speed of motion varying with distance from the tether, and the grafting density (upper) or whether cohesion of the FG repeats results in varying degrees of condensation leading to gels [73,74] (middle) or amyloids [75,76] (lower).