Fig. 1

In silico analysis of potential signal sequence. a The PetD and LHCB1 (TM2-L18-TM3 sequence) proteins sequences from pea were aligned using MAFFT version 7 (Additional file 10: Figure S3, alignment of PetD sequences) [25]. Fully conserved residues are highlighted with a yellow background and functionally conserved residues are shown with a green background. The region corresponding to the PLEIL sequence is bold underlined, and DPLG sequence marked in red italics, TM helices are grey underlined, L18 sequence shown in capital italics [25]. b The Kyte–Doolittle hydropathy profile of the pea PetD (from amino acid numbers 40 to 161, (black line)) and the LHCB1, TM2-L18-TM3 sequences (red line), and the resulting Kyte–Doolittle data were aligned relative to the TM2-L18-TM3 sequence of LHCB1. Both curves display a positive score in the h-region that corresponds to relative hydrophobicity. A relative sequence numbering is given, with position 0 representing the first residue of the LHCB1 TM2, and the window size was set to 5 residues for sequences comparison. c The structure of PetD from Chlamydomonas reinhardtii (pdb 1Q90) with the PLEIL sequence is marked in blue [20]. d The theoretical calculation of the N-terminus of PetD protein was calculated using the bioinformatic tools (TargetP, PSORT and PredSL). Reliability class (RC) indicates the strongest prediction was found with TargetP. ND, not detected; cTP, chloroplast transit peptide