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. 2011 Feb 7;6(2):e16284. doi: 10.1371/journal.pone.0016284

Figure 1. Construction of the expression system.

Figure 1

(A) To identify potentially important domains in the NA stalk, 43 NA sequences covering N1 to N9 from 1918 to 2007 were included in the alignment (for details see Table S1). The inset shows the level of homology of the sequences for the NA domains, namely the cytoplasmatic domain, the transmembrane domain (TM), the stalk- and the head-domain. The alignment shows that although the majority of the stalk is not conserved a small stretch shows a higher degree of similarity. Amino acids 70–73 (based on N2 numbering) of this stretch were included in the expression system (the beginning of the region indicated by red line). (B) The sequences encoding for the 4 artificial NA constructs where cloned into pFastBac upstream from an MSP sequence using EcoRI and XbaI.