Xm. Li et al., CLONING OF THE RAT STEROID SULFATASE GENE (STS), A NON-PSEUDOAUTOSOMAL X-LINKED GENE THAT UNDERGOES X-INACTIVATION, Mammalian genome, 7(6), 1996, pp. 420-424
Although the human steroid sulfatase (STS) gene has been cloned and ch
aracterized in detail, several attempts to clone its mouse homologue,
with either anti-human STS antibodies or human STS cDNA probes, have f
ailed, suggesting a substantial divergence between these genes. Howeve
r, partial amino-terminal sequence from purified rat liver STS is very
similar to its human counterpart, acid sequence comparisons have reve
aled several domains that are conserved among all the sulfatases chara
cterized to date. Thus, we used a degenerate-primer RT-PCR approach to
amplify a 321-bp fragment from rat liver cDNA, which was used as a pr
obe to clone and characterize the complete cDNA. Comparison of the pro
tein coding region between the rat and human genes showed 66% homology
both at the DNA and the protein levels. STS activity was conferred to
STS(-) A9 cells upon transfection with a rat Sts expression construct
, indicating the authenticity of the cloned cDNA. While Sts has been s
hown to be located in the mouse pseudoautosomal region, both physical
and genetic mapping demonstrate that Sts is not pseudoautosomal in the
rat. The overall genomic organization of rat Sts and human STS is ver
y similar, except that the insertion site for intron 1 in the rat is 2
6 bp upstream from that in the human. Rat Srs is only 8.2 kb long, whi
le the human STS spans over 146 kb.