Linked Life Data

9063895

Source:http://linkedlifedata.com/resource/pubmed/id/9063895

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
6
pubmed:dateCreated
1997-3-17
pubmed:databankReference
pubmed:abstractText
The human KB cell or alpha folate receptor (alpha hFR) is a membrane glycoprotein of 42 kDa that participates in the internalization of folates and antifolates. Seven independent alpha hFR cDNA isoforms have been reported that contain unique 5' termini but share a common open reading frame (ORF). To investigate the molecular basis of these heterogeneous 5' sequences, we determined the sequence of the alpha hFR gene from two clones isolated from a human lymphocyte lambda DASH genomic library. The gene is composed of seven exons that span 6.8 kb. The ORF is encoded by exons 4 through 7 while the reported 5' termini of the cDNA isoforms (including two novel cDNAs designated KB2 and KB4) are encoded by exons 1 through 4. Using RNase protection assays, we demonstrate that transcripts corresponding to the KB1 and KB4 cDNAs originate from promoters upstream from exon 1 and exon 4, designated P1 and P4, respectively, and that these mRNA isoforms are the most abundant transcripts expressed in KB cells and selected normal tissues (including kidney, lung, and cerebellum). We observed a heterogeneous start site within exon 1 from the P1 promoter while transcripts from the P4 promoter originate from a single site. In addition, we detected tissue specificity for the P1 and P4 promoter utilization. Transcripts originating from the P1 promoter are the most abundant transcripts expressed by human cerebellum and kidney. In contrast, transcripts from the P4 promoter are the most abundant transcripts expressed by human KB cells and lung. Total RNA from KB cells also protects a 66 bp fragment of an exon 3 riboprobe that is consistent with an alternatively spliced transcript. To examine the functional activity of the predicted P1 and P4 promoters, alpha hFR promoter-CAT chimeric plasmids were constructed using sequences flanking exon 1 and exon 4. We observed a 7.5- and 10-fold increase in CAT activity in HeLa cells transiently transfected with the P1 and P4 promoter constructs, respectively. These data demonstrate that a single gene encodes the divergent 5' termini of the alpha hFR cDNAs and that the alpha hFR transcripts are transcribed from two promoters that are activated in a tissue-specific manner.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Feb
pubmed:issn
0006-2960
pubmed:author
pubmed:issnType
Print
pubmed:day
11
pubmed:volume
36
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
1467-78
pubmed:dateRevised
2010-11-18
pubmed:meshHeading
pubmed-meshheading:9063895-Alternative Splicing, pubmed-meshheading:9063895-Base Sequence, pubmed-meshheading:9063895-Blotting, Southern, pubmed-meshheading:9063895-Carrier Proteins, pubmed-meshheading:9063895-Chloramphenicol O-Acetyltransferase, pubmed-meshheading:9063895-Cloning, Molecular, pubmed-meshheading:9063895-DNA Primers, pubmed-meshheading:9063895-Folate Receptors, GPI-Anchored, pubmed-meshheading:9063895-HeLa Cells, pubmed-meshheading:9063895-Humans, pubmed-meshheading:9063895-Molecular Sequence Data, pubmed-meshheading:9063895-Nucleic Acid Conformation, pubmed-meshheading:9063895-Nucleic Acid Hybridization, pubmed-meshheading:9063895-Promoter Regions, Genetic, pubmed-meshheading:9063895-RNA, Messenger, pubmed-meshheading:9063895-Receptors, Cell Surface, pubmed-meshheading:9063895-Restriction Mapping, pubmed-meshheading:9063895-Transfection
pubmed:year
1997
pubmed:articleTitle
The divergent 5' termini of the alpha human folate receptor (hFR) mRNAs originate from two tissue-specific promoters and alternative splicing: characterization of the alpha hFR gene structure.
pubmed:affiliation
Medicine Branch, National Cancer Institute, Bethesda, Maryland 20892, USA. pce@helix.nih.gov
pubmed:publicationType
Journal Article