Characterization of the human sex hormone binding globulin (SHBG) gene and demonstration of two transcripts in both liver and testis

A genomic cosmid clone for human sex hormone binding globulin (SHBG), a liver-secreted plasma glycoprotein that binds sex steroids, was isolated with a previously characterized liver cDNA as probe. Southern blot analysis of genomic DNA indicated that only one SHBG gene is present in the human haploi...

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Bibliographic Details
Published in:Nucleic acids research 1989-11, Vol.17 (22), p.9245-9258
Main Authors: Gershagen, S, Lundwall, A, Fernlund, P
Format: Article
Language:English
Subjects:
Amino Acid Sequence
Base Sequence
Blotting, Northern
Cloning, Molecular
Cosmids
DNA - genetics
Genes
Humans
liver
Liver - metabolism
Male
Molecular Sequence Data
Oligonucleotide Probes
Restriction Mapping
Sex Hormone-Binding Globulin - genetics
testes
Testis - metabolism
Transcription, Genetic
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Summary:A genomic cosmid clone for human sex hormone binding globulin (SHBG), a liver-secreted plasma glycoprotein that binds sex steroids, was isolated with a previously characterized liver cDNA as probe. Southern blot analysis of genomic DNA indicated that only one SHBG gene is present in the human haploid genome. A 3.8 Kb Xba I-fragment of the clone containing the entire coding region of SHBG was sequenced. The SHBG gene has 8 exons. The 5'-end preceding the translation start site had no TATA box or CAAT box promoter elements. Screening of a human testis cDNA library resulted in the isolation of two distinct cDNA forms. One cDNA was identical with the previously characterized liver SHBG cDNA, thus suggesting that human SHBG and the androgen binding protein (ABP) produced by Sertoli cells are coded for by the same gene. The second cDNA differed from the first by having exon I exchanged with a completely different sequence and exon VII deleted. An exon coding for the 5'-end of this cDNA was found in the cosmid clone 1.5 kb upstream of the first SHBG exon. Primer extension experiments showed the alternatively spliced transcript corresponding to the second cDNA to be present in both liver and testis. From the primary structure of this putative SHBG-gene-related protein, it may be deduced that it is a protein very different from SHBG and probably without steroid binding activity.
ISSN:0305-1048
1362-4962
DOI:10.1093/nar/17.22.9245