Scallop DMT functions as a Ca2+ transporter

We identified a DMT (divalent metal transporter) homologous protein that functions as a Ca2+ transporter. Scallop DMT cDNA encodes a 539-amino-acid protein with 12 putative membrane-spanning domains and has a consensus transport motif in the fourth extracellular loop. Since its mRNA is significantly expressed in the gill and intestine, it is assumed that scallop DMT transports Ca2+ from seawater by the gill and from food by the intestine. Scallop DMT lacks the iron-responsive element commonly found in iron-regulatory proteins, suggesting that it is free of the post-transcriptional regulation from intracellular Fe2+ concentration. Scallop DMT distinctly functions as a Ca2+ transporter unlike other DMTs, however, it also transports Fe2+ and Cd2+ similar to them.