Putative diazepam binding inhibitor peptide: cDNA clones from rat.

Abstract

cDNA clones corresponding to the polypeptide that has been shown to be an endogenous diazepam binding inhibitor and may act as a physiological ligand for the benzodiazepine/beta-carboline receptor have been isolated from bacteriophage lambda recombinant libraries from rat hypothalamus, total brain, and liver. The clones contain an open reading frame corresponding to 87 amino acids. A signal sequence is not present. In addition to high levels of mRNA in various brain regions, RNA blot analysis reveals an abundance of diazepam binding inhibitor mRNA in many peripheral organs (e.g., testes, kidney, liver, and heart) that are known to be rich in peripheral benzodiazepine recognition sites. The size of the mRNA in all tissue examined is approximately 0.7 kilobase. Southern blot analysis of genomic DNA suggests the presence of about six genes in the rat, some of which may be pseudogenes.

Acyl-CoA-binding Protein Is a Potent m-Calpain Activator

“…This protein factor, which induces an approximately 50-fold decrease in the [Ca 2ϩ ] required to activate m-isozymes, has been identified by amino acid sequence analysis as an acyl-CoA-binding protein (13)(14)(15). Recombinant ACBP obtained from E. coli shows the same molecular and functional properties as the m-calpain activator.…”

“…The primers for PCR were selected externally to the translated sequence of mouse brain cDNA for ACBP (accession number X61431). The sense primer was 5Ј-CTTGATTGCTCCTGCTTCTG-3Ј (nucleotides [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20]; the antisense primer was 5Ј-TATGTCCTCACAGGTCACACG-3Ј (complementary to nucleotides 353-373). PCR was carried out by using Amplitaq DNA polymerase and by performing 30 cycles of amplification as described previously (24).…”

“…Despite reports indicating that free calcium ions can be accumulated in specific cell regions at high micromolar concentrations (11), the calcium requirement for m-calpain activation can apparently be satisfied only during tissue necrosis, a situation far removed from physiological conditions (12). We now report that a highly conserved protein, called acylCoA-binding protein (ACBP) 1 (13)(14)(15), shows a potent m-calpain-activating property. This 20-kDa protein, which is involved in various physiological processes including binding to the type-A ␥-aminobutyric acid receptor (16), acyl-CoA binding and transport (17), and steroidogenesis (18), reduces the optimal calcium requirement of m-calpain from 300 M to approximately 10 M. The two calpain activators, UK114 and ACBP, are diversely expressed by many rat tissues, and their levels are inversely correlated with those of the corresponding target calpains.…”

Frog diazepam-binding inhibitor: peptide sequence, cDNA cloning, and expression in the brain.

“…The amino acid sequence of frog DBI deduced from the corresponding cDNA sequence exhibits 80%o similarity with duck DBI (16,17), whereas the similarity with various mammalian DBI ranged between 61% and 68% (10,(12)(13)(14)(15). Evolutionary pressure has particularly acted to conserve the ODN domain, which interacts with both central and peripheral type benzodiazepine receptors (6,20,29) and which binds acyl-CoA esters (17,30).…”

“…The cDNA encoding DBI has been cloned in several mammalian species (12)(13)(14)(15), in birds (16,17), and in yeast (17). Biochemical and immunological studies revealed that DBI-related peptides also occur in the brains of fish (18) and amphibians (19).…”