Output of the REPETITA method. Scatter plot of optimal θ-ratio versus Zmax for the training sets and the human MR repeat region (aa: 174-368). These parameters reflect the existence of a periodic signal in several amino acid properties along the sequence and the largest spectral amplitude of those, respectively. Red and green crosses correspond to solenoid and non-solenoid proteins, respectively. The result corresponding to the human MR repeats is shown as a blue square.