A study of diazepam binding inhibitor (DBI) processing products in human cerebrospinal fluid and in postmortem human brain.
Diazepam binding inhibitor (DBI) is a neuropeptide of 11 kDa molecular size and is unevenly distributed in human and rat brain. It appears to function as a negative allosteric modulator of GABAA receptors. In the present paper, using antibodies directed against several synthetic peptides, which correspond to selective regions of human DBI (DBI 51-70, DBI 37-50, DBI 81-101), it is shown that DBI is processed into at least 6 peptide fragments in both postmortem human brain and in cerebrospinal fluid (CSF). One of these fragments was identified as the synthetic DBI 51-70 fragment (an eikosaneuropeptide, ENP) by combined chromatographic procedures. Immunoblotting analysis of the other fragments, by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (PAGE), revealed an apparent molecular size, ranging from 3-4 kDa for four of them and a larger molecular form of 8 kDa. On the basis of the immunological properties, a tentative amino acid sequence was deduced.
Guarneri
P
P
FIDIA-Georgetown Institute for the Neurosciences, Georgetown University Medical School, Washington, D.C. 20007.
Berkovich
A
A
Guidotti
A
A
Costa
E
E
D000085:Acetates; D000595:Amino Acid Sequence; D001345:Autoradiography; D001923:Brain Chemistry; D002845:Chromatography; D002850:Chromatography, Gel; D002851:Chromatography, High Pressure Liquid; D026261:Diazepam Binding Inhibitor; D004591:Electrophoresis, Polyacrylamide Gel; D006801:Humans; D015151:Immunoblotting; D007457:Iodine Radioisotopes; D008566:Membranes / Q000032:analysis; D008969:Molecular Sequence Data; D008970:Molecular Weight; D009479:Neuropeptides / Q000134:cerebrospinal fluid / Q000378:metabolism*
D000085:Acetates; D026261:Diazepam Binding Inhibitor; D007457:Iodine Radioisotopes; D009479:Neuropeptides