The N TAILD2,3 gene construct, encoding residues 401-488 of the MV N protein with an N-terminal hexahistidine tag plus a C-terminal Flag sequence, previously referred to as N TAIL2 (Bourhis et al. 2004) , was obtained using the plasmid pet21a/ N as template. Forward primer (5 0 -gatagaaccatgCATCATCA TCATCATCATactactgaggacaagatcagtaga-3 0 ) was designed to introduce a hexahistidine tag encoding sequence (upper case) at the N terminus of N TAIL , and reverse primer (5 0 -gtctta TTTGTCGTCATCGTCTTTATAATCactgtcctgcggatcttggctg ga-3 0 ) was designed to introduce a Flag encoding sequence (upper case). The PCR amplification product was further used as template in a second PCR step, using the same pair of primers as in the second PCR step, which yielded the N TAILD3 amplification product. After purification, the PCR product was cloned into the pDest14 vector to yield pDest14/ N TAILD2,3 .