Open AccessDegradation of abnormal proteins in intact mouse reticulocytes: accumulation of intermediates in the presence of bestatin.
Author(s) -
Violeta Botbol,
Oscar A. Scornik
Publication year - 1979
Publication title -
proceedings of the national academy of sciences of the united states of america
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.011
H-Index - 771
eISSN - 1091-6490
pISSN - 0027-8424
DOI - 10.1073/pnas.76.2.710
Subject(s) - sephadex , cycloheximide , ninhydrin , biochemistry , trichloroacetic acid , amino acid , chemistry , tripeptide , hydrolysis , leucine , incubation , in vivo , hydrolysate , peptide , protein degradation , protein biosynthesis , in vitro , chromatography , enzyme , biology , microbiology and biotechnology
Incubation of intact mouse reticulocytes with bestatin (a competitive inhibitor of aminopeptidases) produced the accumulation of low molecular weight intermediates in the degradation of puromycinyl-peptides or analog-containing proteins that had been pulse labeled with L-[1-14C]leucine. A large fraction of the radioactive protein was degraded to trichloroacetic acid-soluble products within 10 min. In the presence of bestatin (0.5 mg/ml), one-fourth of these products appeared to be dipeptides, tripeptides, or both: they were resistant to ninhydrin at acid pH (a treatment that decarboxylates only free amino acids) except after intensive acid hydrolysis, and they eluted from a Sephadex G-10 column with an apparent average size of 300 daltons. These radioactive products did not appear if incorporation of the tracer was prevented by prior treatment with cycloheximide, demonstrating that they originated from polypeptide precursors. Thus, a peptidase inhibitor has been successfully used in the production of low molecular weight intermediates in the in vivo degradation of cellular proteins.