Arabidopsis MTM1 and MTM2 are homologs of yeast MTM1
The sequence alignment of AtMTM2, AtMTM1, and yMTM1 showed high
similarity (Supplemental Figure S1) . Each protein sequence
consists of three tandemly homologous domains (blue underline), and each
repeat domain contains two transmembrane α-helices (yellow shading).
Three copies of a 10-amino acid sequence motif (I, II, and III) known as
the METS are the structural features of MCF carriers. Besides, they
share the conserved substrate Mn-binding site (red double-headed arrow).
Protein BLAST (http://blast.ncbi.nlm.nih.gov/Blast.cgi) revealed
AtMTM1 has 32% protein sequence identity with yMTM1; AtMTM2 has 34%
protein identity with yMTM1 and 59% identity with AtMTM1. Sequence
alignment and motif analysis revealed AtMTM1 and AtMTM2 could be
homologs of the yeast MCF protein yMTM1. As noted, AtMTM1 was suggested
as the yMTM1 homolog in Arabidopsis (Su et al., 2007).