Biochem. J. (1999) 340
(255–264) (Printed in Great Britain)
Human stearoyl-CoA desaturase: alternative transcripts generated from a single gene by usage of tandem polyadenylation sites
Lin ZHANG, Lan GE, Satish PARIMOO, Kurt STENN and Stephen M. PROUTY1
Skin Biology T. R. C., Johnson and Johnson, C. P. W. W., Skillman, NJ 08558, U.S.A.
A critical step in the synthesis of unsaturated fatty acids is catalysed
by stearoyl-CoA desaturase (Scd). To determine the regulation of human
Scd, we characterized the gene and its transcripts. Screening a human keratinocyte
cDNA library and analysis of 3´-RACE (rapid amplification of cDNA
ends) products from various tissues yielded a 5.2 kb cDNA encoding
a 359 amino acid protein with a calculated molecular mass of 41.5 kDa.
Analysis of 3´-RACE products suggested that alternative usage of polyadenylation
sites generates two transcripts of 3.9 and 5.2 kb, a result consistent
with Northern analysis. Southern analysis demonstrated the existance of
two SCD loci in the human genome. Chromosomal mapping localized
one locus to chromosome 10, and the second locus to chromosome 17. Characterization
of genomic clones isolated from chromosome-specific libraries revealed
that only the locus on chromosome 10 contained introns. Sequence analysis
of the intron-less locus displayed multiple nucleotide insertions and deletions,
as well as in-frame stop codons. Reverse transcriptase-PCR analysis performed
with primers specific to the intron-less locus failed to produce a PCR
product from brain, liver and skin RNA, indicating that the locus on chromosome
17 is most likely a transcriptionally inactive, fully processed pseudogene.
These results suggest strongly that there is one structural SCD
gene in the human genome, and that it generates two transcripts by use
of alternative polyadenyation sites. Although the primary sequence and
intron–exon structure of SCD is phylogenetically conserved,
divergence between rodent and human is seen in the number of SCD
genes and in the generation of alternative transcripts, suggesting a species-specific
component of SCD regulation and function.
Abbreviations used: RACE, rapid amplification of cDNA ends;
SCD,
Scd, stearoyl-CoA desaturase gene and mRNA/cDNA/protein, respectively;
RFLP, restriction fragment length polymorphism; RT, reverse transcriptase.
1
To whom correspondence should be addressed (e-mail sprouty@cpcus.jnj.com).
The nucleotide sequence reported in this paper has been submitted to
the GenBank database with accession number AF097514.
Key words: enzymes,
Homo sapiens, lipid metabolism, monosaturated
fatty acid, oleic acid.
Received 2 November 1998/20 January 1999; accepted 23 February 1999
The Biochemical Society, London © 1999
About
Full Editorial Board
RSS feeds
Table of contents by email
My BJ toolbox
