Peptide mapping of fat cell membrane substrates for cholera toxin-catalyzed ADP-ribosylation |
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Authors: | Craig C Malbon |
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Institution: | Department of Pharmacological Sciences, Health Sciences Center, State University of New York at Stony Brook, Stony Brook, NY 11794 U.S.A. |
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Abstract: | Incubating rat fat cell membranes with 32P]NAD+ and cholera toxin results in ADP-ribosylation of three distinct components with approximate molecular weights of 42 000, 46 000 and 48 000. Partial proteolytic peptide maps of the Mr = 46 000 and 48 0000 toxin-specific substrates generated by elastase, α-chymotypsin, or Staphylococcus aureus V-8 protease were nearly identical, while those of the Mr = 42 000 target lacked several peptides common to both of the larger molecular weight targets. In addition, peptide maps generated from the Mr = 42 000 target displayed a number of peptides which were absent from the maps generated from either the Mr = 46 000 or 48 000 targets. These data suggest that the Mr = 46 000 and 48 000 substrates are closely related proteins, however the relationship between the Mr = 42 000 toxin-specific substrate and the larger peptides remains to be established. The relative patterns of fat cell membrane labelling by cholera toxin in the presence of 32P]NAD+ |
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Keywords: | Peptide mapping Cholear toxin ADP-ribosylation (Fat cell membrane) were identical in hypothyroid as compared to euthyroid rat fat cells |
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