Fig. 6

Critical sites for CG4562/dMRP5 heme transport. A CG4562/dMRP5 structure was homology modeled based on human CFTR. The transmembrane domain TMD1 (green), TMD2 (cyan), and NBD domains (gray) are marked respectively. The side chains of functional residues in TMD1 and TMD2 are labeled in red. B, C Potential heme-binding amino acids, of which side chains are inward were selected and mutated into alanine. ZnMP retention signals were analyzed with S2 cells expressing CG4562/dMRP5 TMD1 (B) and TMD2 (C) mutants. All values are available in Additional file 3: Fig. 6B and Fig. 6C. D The nucleotide binding domains of CG4562/dMRP5. NBD1 (wheat) and NBD2 (green) form two ATP binding sites consisted of the consensus site (blue box) and the degenerate site (purple box). E Detailed features of the consensus and degenerate sites are shown and key amino acid residues are highlighted (red). F, G Key amino acids from the consensus (F) and degenerate (G) sites were mutated. ZnMP signal density was analyzed. Zoom-in views of the consensus and degenerate sites are on the right side. All values are available in Additional file 3: Fig. 6F and Fig. 6G. Data are presented as means ± SD by two-tailed unpaired Student’s t test. *p < 0.05, **p < 0.01; ***p < 0.001. Experiments were repeated at least two times, and data from only one representative experiment were shown