Genomic structure of the gene for mouse germ-cell nuclear factor (GCNF). II. Comparison with the genomic structure of the human GCNF gene.
BACKGROUND
Germ-cell nuclear factor (GCNF, NR6AI) is an orphan nuclear receptor. Its expression pattern suggests it functions during embryogenesis, in the placenta and in germ-cell development. Mouse GCNF cDNA codes for a protein of 495 amino acids, whereas the four reported human cDNA variants code for proteins of 454 to 480 amino acids. Apart from this size difference, there is sequence conservation of up to 98.7%. To elucidate the genomic structure that gives rise to the different human GCNF mRNAs, the sequence information of the human GCNF locus is compared to the previously reported structure of the mouse locus.


RESULTS
The genomic structures of the mouse and human GCNF genes are highly conserved. The comparison reveals that the shorter human protein results from skipping the 45 base-pair third exon. Three different human isoforms - GCNF-1, GCNF-2a and GCNF-2b - are generated by differential usage of alternative splice acceptor sites of the fourth and the seventh exon.


CONCLUSIONS
By homology with the mouse gene, 11 GCNF coding exons can be defined on human chromosome 9. All human GCNF cDNAs identified so far are, however, derived from mRNAs generated by splicing the fourth to the second exon. Although the genomic sequence is highly conserved, the analysis suggests that alternative splicing generates a higher complexity of human GCNF isoforms compared with the situation in the mouse.
Süsens
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U
Zentrum für Molekulare Neurobiologie, Universität Hamburg, Martinistrasse 52, D-0246 Hamburg, Germany.
Borgmeyer
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U
D017398:Alternative Splicing; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D017124:Conserved Sequence; D004268:DNA-Binding Proteins / Q000235:genetics*; D005091:Exons; D005796:Genes; D006801:Humans; D051379:Mice; D008969:Molecular Sequence Data; D057136:Nuclear Receptor Subfamily 6, Group A, Member 1; D018160:Receptors, Cytoplasmic and Nuclear / Q000235:genetics*; D018168:Receptors, Retinoic Acid; D012689:Sequence Homology, Nucleic Acid
D004268:DNA-Binding Proteins; C539950:NR6A1 protein, human; C539954:Nr6a1 protein, mouse; D057136:Nuclear Receptor Subfamily 6, Group A, Member 1; D018160:Receptors, Cytoplasmic and Nuclear; D018168:Receptors, Retinoic Acid