Characterisation of the rat acid-labile subunit gene.
The acid-labile subunit (ALS) of the ternary insulin-like growth factor binding protein (IGFBP) complex has a central role in regulating the bioavailability of circulating IGF. We have shown that gene expression of ALS in vivo and in vitro is regulated by a variety of factors, including growth hormone (GH). Our aim was to isolate and characterise the ALS gene as a step in defining the mechanism of its regulation. Southern analysis of rat genomic DNA suggests that the ALS gene exists as a single copy in the rat genome. In order to isolate this gene we screened 5 x 10(5) clones and selected fragments of two genomic clones were sequenced. Comparison of this sequence with the cDNA identified two exons and a single approximately 1.1 kb intron. Primer extension experiments suggest two major transcription initiation sites at -539 and -396 nts relative to the translational initiation codon, although there are no consensus TATA-boxes in this region. Analysis of 2.3 kb of 5' flanking sequence identified two LF-A1 sites which may confer the liver-specific expression of the ALS gene. In addition, there are several elements that may be involved in regulation by growth hormone and cytokines.
Delhanty
P J
PJ
Kolling Institute of Medical Research, Royal North Shore Hospital, St Leonards, NSW, Australia.
Baxter
R C
RC
D033965:Adaptor Protein Complex alpha Subunits; D033942:Adaptor Proteins, Vesicular Transport; D000818:Animals; D001665:Binding Sites; D015139:Blotting, Southern; D002352:Carrier Proteins / Q000737:chemistry* / Q000235:genetics; D002874:Chromosome Mapping; D017362:Cyclic AMP Response Element-Binding Protein / Q000378:metabolism; D004247:DNA / Q000737:chemistry; D005091:Exons; D006023:Glycoproteins / Q000737:chemistry* / Q000235:genetics; D008565:Membrane Proteins / Q000378:metabolism; D051381:Rats; D015183:Restriction Mapping; D017422:Sequence Analysis, DNA; D013002:Somatomedins / Q000378:metabolism*; D014158:Transcription, Genetic
D033965:Adaptor Protein Complex alpha Subunits; D033942:Adaptor Proteins, Vesicular Transport; D002352:Carrier Proteins; D017362:Cyclic AMP Response Element-Binding Protein; D006023:Glycoproteins; D008565:Membrane Proteins; D013002:Somatomedins; C075944:insulin-like growth factor binding protein, acid labile subunit; D004247:DNA