title: Alternative transcripts of rat slc19a1: cloning, genomic organisation, tissue specific promoters and alternative splicing.
abstract: Recently, the rat genome project revealed the genomic sequence of slc19a1, coding for the methotrexate carrier-1, identical to the reduced folate carrier-1 of humans, on rat chromosome 20. At the same time, we have cloned and analysed the complete or partial cDNAs of now at least six different transcripts from rat liver and kidneys. Alignment with the genomic sequence revealed seven exons. The first two non-coding exons, exon I and Ia were used alternatively in kidneys and liver, respectively, suggesting usage of alternative promoters. Three minor mRNA forms resulted from absent splicing of intron III, a shortened exon III (exon IIIa), and a shortened exon IV (exon IVa). The minor transcripts were predicted to result in translation products with 7 or 6 instead of 12 transmembrane domains (TMDs) and a peptide mass of 38, 39 and 40 kDa instead of 58 kDa.
authors.affiliation: Faculty of Veterinary Medicine, Institute of Pharmacology, Pharmacy and Toxicology, University of Leipzig, Germany.
authors.forename: Carsten
authors.initials: C
authors.lastname: Kneuer
authors.forename: Stephanie
authors.initials: S
authors.lastname: Schrader
authors.forename: Walther
authors.initials: W
authors.lastname: Honscha
mesh_terms: D017398:Alternative Splicing; D000818:Animals; D001483:Base Sequence; D003001:Cloning, Molecular; D005091:Exons; D016678:Genome; D007438:Introns; D007668:Kidney / Q000378:metabolism; D008099:Liver / Q000378:metabolism; D026901:Membrane Transport Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D015778:Minor Histocompatibility Antigens; D008958:Models, Molecular; D008970:Molecular Weight; D011401:Promoter Regions, Genetic; D011487:Protein Conformation; D017434:Protein Structure, Tertiary; D012333:RNA, Messenger / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D051381:Rats; D058978:Reduced Folate Carrier Protein; D014018:Tissue Distribution
chemical_list: D026901:Membrane Transport Proteins; D015778:Minor Histocompatibility Antigens; D012333:RNA, Messenger; D058978:Reduced Folate Carrier Protein; C043408:Slc19a1 protein, rat