Proteolysis of puromycin‐peptides in rabbit reticulocytes: detection of a high molecular weight oligopeptide proteolytic substrate

Abstract

Many types of cells (~sc~e~c~~ co& HeLa, human fibroblast, rat hepatoma, and the reticulocyte of the rat, mouse and rabbit) have the capability to degrade selectively proteins whose structures deviate significantly from that of normal gene products; such proteins are termed abnormal [I].The mechanism of this selective proteolysis is unclear although it may be ener~dependent [2,3 J.In the present study we have induced the synthesis of Iabelled protein of shortened chain length in rabbit reticulocytes by incubation with the antibiotic puromycin, a chain terminator, and monitored, by gel ~ltration, subsequent changes in protein size.We show that puromycin promotes the synthesis of high MW (over 100 000) peptide aggregates which rapidly disappear after removal of the ~tibiotic: we suggest that these peptide complexes may be proteolytic substrates in the degradative process.