Rat prominin, like its mouse and human orthologues, is a pentaspan membrane glycoprotein

Mouse prominin is the first characterized member of a novel family of membr ane glycoproteins. It displays characteristic membrane topology with five t ransmembrane segments and two large glycosylated extracellular loops. Promi nin orthologues and paralogues have been identified in human, fish, fly, an d worm. Recently, a cDNA sequence encoding the rat homologue of mouse promi nin has been reported [Zhu et al (2001) Biochem. Biophys. Res. Commun. 281, 951-956]. Surprisingly, due to a single nucleotide deletion that shifts th e reading frame and introduces a premature stop codon, the protein predicte d from this cDNA would correspond to a C-terminally truncated form of promi nin with only four transmembrane segments. Here we report evidence that is in contrast to the report of Zhu et al (2001). We isolated a rat prominin c DNA devoid of any frameshift mutation, demonstrate that rat prominin, like the other mammalian prominins, is a full-length 120-kDa pentaspan membrane glycoprotein, and have not been able to detect any C-terminally truncated f orm of rat prominin. (C) 2001 Academic Press.