Human UDP-galactose translocator: molecular cloning of a complementary DNA that complements the genetic defect of a mutant cell line deficient in UDP-galactose translocator.

We have cloned a cDNA that codes for a putative human UDP-galactose translocator (UGT) protein. The cDNA contained an open reading frame of 1,179 base pairs encoding a novel protein of 393 amino acids. Introduction of the open reading frame sequence into a UGT-deficient mouse cell line, Had-1, complemented the genetic defect of the mutant, namely the inability to transport UDP-galactose from the cytosol to the Golgi lumen, as judged from the lectin-sensitivity spectrum of the transformant. To our knowledge, this is the first mammalian nucleotide-sugar translocator whose cDNA sequence has been described.