Sequence analysis and topology of the predicted transmembrane helices in ferroportin 1.

The software packages used were: TM pred, TMAP, and DAS via the PIX program at www.hgmp.mrc.ac.uk/; SOSUI (www.tuat.ac.jp/∼mitaku/); TopPred2 (bioweb.pasteur.fr/seqanal/interfaces/toppred.html); TMHMM2.0 (www.cbs.dtu.dk/services/TMHMM-2.0/); HMMTOP2 (www.enzim.hu/hmmtop/); and PHDhtm/PHDtopology (www.embl-heidelberg.de/predictprotein/predictprotein.html). The sequence accession numbers were: human, NM_014585; mouse, NM_016917; rat, AF394785; and zebrafish, AF226612. In NM_016917, the unspecified amino acid Xaa365 was specified as Arg365 by comparison with AF215637. (A) The sequence is annotated in order to identify the consensus transmembrane helices predicted from 8 methods and the locations of the 4 mutations identified to date in human and zebrafish ferroportin 1 (bold and underlined). The zebrafish Leu167Phe mutation is responsible for the hypochromic anemia weissherbstphenotype.2 Leu167Phe in zebrafish is equivalent to Leu170Phe in the predicted human sequence. The sequence numbering is denoted by a vertical stroke at every fifth residue and the bracketed number at the end of each line. The locations of the 12 Cys residues (*) and 3 extracellular putative N-linked oligosaccharide sites (#) are in bold type and underlined (see text). (B) The 9 predicted transmembrane helices (1-9) are shown in relation to the lipid bilayer, with the positions of the 4 mutations (red circles), 12 Cys residues (yellow circles), and 3 putative exposed N-linked oligosaccharide sites (Y) marked as shown. The N- and C-termini are denoted by N and C, respectively. The residue length of each ferroportin 1 loop is denoted by the numbers adjacent to each one.