We have previously shown that N TAIL belongs to the premolten globule subfamily, e.g., it possesses a certain extent of residual secondary and/or tertiary structure Bourhis et al. 2004 ). In agreement with these findings, NMR studies showed that the N TAIL region encompassing residues 486-503 is not a statistical random coil (Kingston et al. 2004a ). These results, supporting a restricted conformational freedom of this N TAIL region, are in agreement with the speculation that residual structure within N TAIL may play a role for efficient binding to P Bourhis et al. 2004) . That residual structure within intrinsically disordered proteins may favor the folding process triggered by binding to a partner has already been reported (Bienkiewicz et al. 2002; Fuxreiter et al. 2004; Csizmok et al. 2005) .