Occurrence of beta-turn potentials around nuclear and nucleolar localization sequences.

The biological significance of turn structures is now of great topical interest. By using the protein conformational prediction method of Chou and Fasman, the present work predicts that 17 nuclear localization signals and a nucleolar localization signal reported so far contain turn potentials. Two nuclear localization signals, human lamin A and c-myc protein (peptide M1), however, cannot be predicted as containing beta-turns by the prediction method. To date, no physical characterization of any nuclear or nucleolar location signal by X-ray crystallography and nuclear magnetic resonance spectroscopy has been performed. Employing conformation prediction methods, therefore, would be useful for elucidating structural features of nuclear and nucleolar location signals.