The grid-search function in NMRdyn can be used to study protein self-association. For example, a floating-stoichiometry analysis can be performed to determine the form of the aggregate by searching over a grid with various values for the association constant, Ka, and the size of the oligomer, which can be manipulated in NMRdyn through an interactive input panel. Floating-stoichiometry analysis has been used previously to determine the stoichiometry of oligomers, e.g. a floating-stoichiometry analysis of tyrosine phosphatase suggested that it can form Imperialine-D-glucoside tetramers in solution. Our previous analyses of the transgenic lines produced showed that the LacZ and PPT-A genes were being correctly anatomically expressed in the central and peripheral nervous system. Although the respiratory tract has an extensive network of peptidergic MI-538 innervation, in this study, epithelial cells lining the air passages of 143-YAChPPT-ALacZ mice were found to be transcribing htPPT-A mRNA in response to viral infection, as shown by the presence of blue staining in the airways corresponding to expression of the marker gene LacZ. Given that these animals produced the expected patterns of the endogenous PPT-A gene in the rodent nervous system we have no reason to believe that the use of the human allele would have inappropriate expression in the lung. However, we confirmed synthesis of SP protein in these cells by immunostaining for SP in both transgenic and non-transgenic animals. In the non-transgenic animals, the SP produced can only be synthesised by the mouse gene. Further, we saw a similar pattern of SP-specific staining in the two mouse strains, indicating that the induction is not a strain specific response. We have shown production of SP peptide by airway epithelial cells. PPT-A precursor protein needs to be processed into its constituent peptides by neutral endopeptidase before it becomes active. One concern therefore was that the nascent tachykinin peptide produced by epithelial cells might not be processed into active protein.The htPPT-A transgenic model which co-ordinately expresses the LacZ marker allowed us not only to determine which cells were expressing PPT-A in response to challenge but also permitted us to determine the temporal cascade of expression.