Figure 1
(A) Homology between the PIF clone 607227, DSEP and dermcidin cDNAs. Clone 607227 was identified by screening the Lifeseq Foundation database (Incyte) for sequences which, when translated, showed a high degree of homology to the PIF amino-acid sequence. A high degree of homology between the translated and untranslated sequences of the three cDNAs can also be seen to exist. The 330 bp ORF is 100% homologous in all sequences. (B) Amino-acid homology between PIF, Y-P30 and dermcidin. Proteolysis-inducing factor shares all but three amino acids with the predicted dermcidin protein and mismatches may be the result of sequencing artefact resulting in the conversion of cysteine to serine (Todorov et al, 1996). Similarly, only the two unidentifiable amino acids of Y-P30 (Cunningham et al, 1998) do not match with the predicted dermcidin protein. These results are subsequently consistent with both the PIF core peptide and Y-P30 arising from the dermcidin protein. The sequence of the dermcidin peptide DCD-1 does not overlap with that of Y-P30 or the PIF core peptide. (C) Diagram of the PIF protein arrangement showing sites of signal peptide, Y-P30 and DCD-1 cleavage. Asparagine and serine residues, which are the only potential N- and O-glycosylation sites, respectively, are underlined and can be seen to lie in the Y-P30 sequence, with the exception of the four serine residues of DCD-1. The Y-P30 and DCD-1 sequences were derived as described (Cunningham et al, 1998; Schittek et al, 2001). The signal peptide sequence and N- and O-glycosylation sites were derived by computer modelling using SignalP, Net-N-Glyc and Net-O-Glyc, respectively.
