Putative diazepam binding inhibitor peptide: cDNA clones from rat.

Area of Science:

• Neuroscience
• Molecular Biology
• Pharmacology

Background:

• The diazepam binding inhibitor (DBI) is an endogenous polypeptide.
• DBI may function as a physiological ligand for the benzodiazepine/beta-carboline receptor.
• Benzodiazepine receptors are found in both the central nervous system and peripheral tissues.

Purpose of the Study:

• To isolate cDNA clones encoding the diazepam binding inhibitor.
• To investigate the distribution of diazepam binding inhibitor mRNA in rat tissues.
• To explore the genetic basis of the diazepam binding inhibitor in rats.

Main Methods:

• Isolation of cDNA clones from rat brain and liver using bacteriophage lambda recombinant libraries.
• RNA blot analysis to determine mRNA distribution and size.
• Southern blot analysis to assess the number of diazepam binding inhibitor genes.

Main Results:

• cDNA clones encoding an 87-amino acid polypeptide (DBI) were isolated.
• DBI mRNA is highly abundant in various brain regions and peripheral organs (testes, kidney, liver, heart).
• The size of DBI mRNA is approximately 0.7 kilobase across all examined tissues.
• Southern blot analysis suggests the presence of about six DBI genes in the rat genome.

Conclusions:

• The diazepam binding inhibitor (DBI) is expressed in both the brain and peripheral organs rich in benzodiazepine recognition sites.
• The widespread distribution of DBI mRNA suggests a significant physiological role beyond the central nervous system.
• The rat genome contains multiple genes related to diazepam binding inhibitor, possibly including pseudogenes.