Sodium Dependent Dicarboxylate Cotransporter 1 (NADC1)

The composite human NADC1 cDNA sequence predicts a 593-amino acid protein containing at least 8 transmembrane domains, 2 potential N-glycosylation sites, and 2 potential protein kinase C phosphorylation sites. The deduced amino acid sequence of human NADC1 is 78% identical to that of rabbit NADC1 and 47% identical to that of the rat kidney sodium-sulfate transporter NaSi1. In vitro translation of human NADC1 produced an approximately 48-kD protein; its mass increased to approximately 59 kD in the presence of pancreatic microsomes, indicating that core glycosylation had occurred. Recombinant human NADC1 expressed in Xenopus oocytes transported both succinate and citrate. It was a low-affinity, sodium-dependent, and pH-insensitive transporter of succinate.