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).