Coding sequence, genomic organization and expression of a folate binding protein gene in the rat

The complementary DNA (cDNA) and the gene encoding the folate binding prote in alpha isoform (FBP alpha) have been reported for the human and mouse pro tein. However, there is no information about this gene in the rat, an anima l that could be a model to study expression of this protein in vivo when fo late metabolism is modified. Accordingly, the cloning and characterization of this gene in the rat have been the subject of this research. The gene ha s seven exons and six introns and is approximately 10 kb in size. The organ ization and nucleotide sequence of the coding exons are similar to those of the corresponding human and mouse genes, which are the only other mammalia n FBP genes cloned. However, the amino acid sequence of the rat FBP alpha i s less homologous, having 48% identity with the published sequences for all the mammalian FBP isoforms. A finding not previously reported is the expre ssion of two FBP alpha transcripts in the kidney that differ in the length of the 5' untranslated sequences, as determined by rapid amplification of c DNA end-polymerase chain reaction amplification (RACE-PCR). The brain expre sses a single transcript intermediate in size between the two transcripts e xpressed in the kidney. The kidney transcripts are encoded by the same gene and appear to be regulated either from two independent promoters or from a single promoter in association with alternative RNA splicing. (C) 2000 Els evier Science B.V. All rights reserved.