TY - JOUR
T1 - Organization of the murine reduced folate carrier gene and identification of variant splice forms
AU - Brigle, Kevin E.
AU - Spinella, Michael J.
AU - Sierra, Esteban E.
AU - Goldman, I. David
N1 - Funding Information:
Supported by NCI grants CA-39807, CA-09340, and CA-09349.
PY - 1997/8/7
Y1 - 1997/8/7
N2 - RT-PCR analysis of the reduced folate carrier (RFC) from L1210 and murine erythroleukemia cells led to the identification of three clones which appeared to result from the use of alternative splice sites. The nucleotide sequence of each splice form predicts a protein that contains at least the first 7 transmembrane domains of the parental RFC protein followed by a novel hydrophilic carboxyl terminus of 33, 72, or 105 amino acid residues. Sequence analysis of cDNA clones isolated from murine liver and the results of 5'- RACE from L1210 cells indicated that RFC also utilizes alternate 5'-terminal exons. To understand how the alternatively spliced RFC transcripts and multiple 5'-termini were generated, the genomic organization of RFC was determined. The gene is comprised of at least 8 exons, the first two of which encode the alternative 5' termini. Based on sequence identity with cDNAs encoding RFC from hamster and rat, however, it appears that additional 5' exons may be present. Two of the RFC splice variants result from the use of a cryptic splice donor site within exon 4 and the third results from the use of a cryptic splice acceptor site within exon 5. In addition, the splice variant form that encodes the largest protein also utilizes an alternative exon located between exons 5 and 6. The apparent use of alternative transcriptional start sites and the identification of several RFC splice forms raises the possibility that unique RFC molecules may be generated that exhibit tissue- or cell line-specific distribution.
AB - RT-PCR analysis of the reduced folate carrier (RFC) from L1210 and murine erythroleukemia cells led to the identification of three clones which appeared to result from the use of alternative splice sites. The nucleotide sequence of each splice form predicts a protein that contains at least the first 7 transmembrane domains of the parental RFC protein followed by a novel hydrophilic carboxyl terminus of 33, 72, or 105 amino acid residues. Sequence analysis of cDNA clones isolated from murine liver and the results of 5'- RACE from L1210 cells indicated that RFC also utilizes alternate 5'-terminal exons. To understand how the alternatively spliced RFC transcripts and multiple 5'-termini were generated, the genomic organization of RFC was determined. The gene is comprised of at least 8 exons, the first two of which encode the alternative 5' termini. Based on sequence identity with cDNAs encoding RFC from hamster and rat, however, it appears that additional 5' exons may be present. Two of the RFC splice variants result from the use of a cryptic splice donor site within exon 4 and the third results from the use of a cryptic splice acceptor site within exon 5. In addition, the splice variant form that encodes the largest protein also utilizes an alternative exon located between exons 5 and 6. The apparent use of alternative transcriptional start sites and the identification of several RFC splice forms raises the possibility that unique RFC molecules may be generated that exhibit tissue- or cell line-specific distribution.
KW - Folate transport
KW - Genomic organization
KW - Methotrexate transport
KW - Reduced folate carrier
KW - Reduced folate carrier 1
KW - Splice form
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U2 - 10.1016/S0167-4781(97)00082-1
DO - 10.1016/S0167-4781(97)00082-1
M3 - Article
C2 - 9294013
AN - SCOPUS:0030790240
SN - 0167-4781
VL - 1353
SP - 191
EP - 198
JO - Biochimica et Biophysica Acta - Gene Structure and Expression
JF - Biochimica et Biophysica Acta - Gene Structure and Expression
IS - 2
ER -