The rat vitamin D binding protein (Gc-globulin) gene. Structural analysis, functional and evolutionary correlations

Area of Science:

• Genomics
• Molecular Biology
• Evolutionary Biology

Background:

• The vitamin D binding protein (DBP) plays a crucial role in vitamin D transport and metabolism.
• Understanding the genetic regulation and evolutionary history of DBP is essential for comprehending its function.

Purpose of the Study:

• To clone and comprehensively characterize the complete rat vitamin D binding protein (DBP) gene.
• To analyze the gene's structure, including exons, introns, and flanking regions.
• To investigate the evolutionary relationship of the DBP gene with related genes like albumin and alpha-fetoprotein.

Main Methods:

• Genomic cloning and characterization of the rat DBP gene.
• DNA sequencing of exons, exon/intron boundaries, and the 5'-flanking region.
• Primer extension analysis to determine the transcription cap site.
• Comparative sequence analysis with human, albumin, and alpha-fetoprotein genes.

Main Results:

• The complete rat DBP gene spans 35 kilobase pairs and contains 13 exons.
• Sequencing identified the transcription start site and a potential surrogate TATA box (TGTAAA motif).
• The promoter region shows similarity to the human DBP gene and contains conserved elements, suggesting regulatory roles.
• Intron locations are conserved with albumin and alpha-fetoprotein genes.
• Evolutionary analysis indicates the loss of exons 12 and 13 in the DBP gene lineage.

Conclusions:

• The rat DBP gene structure and regulatory regions have been elucidated.
• Conserved elements in the 5'-flanking region suggest important promoter functions.
• The evolutionary divergence of the DBP gene from its progenitors involved the loss of specific exons, explaining its smaller protein size.