Premium
Photolabeled tryptic degradation products of benzodiazepine‐binding proteins are glycopeptides Implications for localization of cleavage sites
Author(s) -
Schmitz Elke,
Reichelt Ralf,
Möhler Hanns,
Hebebrand Johannes
Publication year - 1989
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(89)80578-2
Subject(s) - chemistry , endoglycosidase , flunitrazepam , trypsin , photoaffinity labeling , trypsinization , biochemistry , transmembrane domain , proteolysis , cleavage (geology) , receptor , gel electrophoresis , endoglycosidase h , protein subunit , polyacrylamide gel electrophoresis , microbiology and biotechnology , benzodiazepine , biology , enzyme , golgi apparatus , paleontology , fracture (geology) , gene , cell
Crude synaptic membranes of avian and mammalian brain tissue were photolabeled with the benzodiazepine‐receptor ligand [ 3 H]flunitrazepam and subsequently treated extensively with trypsin followed by incubation with endoglycosidase F. SDS‐polyacrylamide gel electrophoresis and fluorography revealed that the final tryptic degradation product of 25 kDa in both pigeon and calf brain is deglycosylated in two steps. These results were confirmed by immunoblots of similarly pretreated membranes of pig brain using the α‐subunit‐specific monoclonal antibody bd‐24. Benzodiazepine‐receptor binding and its enhancement by GABA are largely retained after trypsinization. Based on the proposed transmembrane topology for the α‐subunits of the GABA/benzodiazepine receptor, we suggest that the large N‐terminal domain of benzodiazepine‐binding proteins is protected against tryptic cleavage.