Genomic Structure of the POU-Related Hepatic Transcription Factor HNF-1α

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Abstract
Hepatocyte Nuclear Factor-1 alpha (HNF-1 alpha) is a vertebrate transcriptional regulatory protein which plays a prominent role in the activation of a large family of hepatocyte-specific genes. It is the prototype of a new subfamily of POU-related proteins important in embryogenesis and cell-type specification. Here we report on the genomic structure and DNA sequence of HNF-1 alpha of the hen. Functional domains are non-uniformly conserved between hen and mammals consistent with the notion of functions in the hen oviduct that were lost in mammals after avian mammalian separation. The unusual homeo-related DNA-binding domain is well preserved between birds and mammals. The exon/intron pattern of the gene changed during evolution. The rat gene consists of 9 exons, the chicken gene of 10. In mammals one intron was eliminated that in hens subdivides the serine-rich transactivation domain. Comparison of the sequences at this junction indicates the involvement of elements of the V(D)J recombination system in the process of intron elimination.