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Titolo:
REGULATED CO-TRANSLATIONAL UBIQUITINATION OF APOLIPOPROTEIN - B100 A NEW PARADIGM FOR PROTEASOMAL, DEGRADATION OF A SECRETORY PROTEIN
Autore:
ZHOU MY; FISHER EA; GINSBERG HN;
Indirizzi:
COLUMBIA UNIV COLL PHYS & SURG,DEPT MED,P&S 9-510,630 W 168TH ST NEW YORK NY 10032 COLUMBIA UNIV COLL PHYS & SURG,DEPT MED NEW YORK NY 10032 MT SINAI SCH MED,CARDIOVASC INST NEW YORK NY 10025
Titolo Testata:
The Journal of biological chemistry
fascicolo: 38, volume: 273, anno: 1998,
pagine: 24649 - 24653
SICI:
0021-9258(1998)273:38<24649:RCUOA->2.0.ZU;2-Q
Fonte:
ISI
Lingua:
ENG
Soggetto:
TRIGLYCERIDE TRANSFER PROTEIN; B-CONTAINING LIPOPROTEINS; HEP G2 CELLS; ENDOPLASMIC-RETICULUM; INTRACELLULAR DEGRADATION; QUALITY-CONTROL; TRANSLOCATION; PATHWAY; HEAT-SHOCK-PROTEIN-70; ABETALIPOPROTEINEMIA;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Citazioni:
37
Recensione:
Indirizzi per estratti:
Citazione:
M.Y. Zhou et al., "REGULATED CO-TRANSLATIONAL UBIQUITINATION OF APOLIPOPROTEIN - B100 A NEW PARADIGM FOR PROTEASOMAL, DEGRADATION OF A SECRETORY PROTEIN", The Journal of biological chemistry, 273(38), 1998, pp. 24649-24653

Abstract

Presentation of a wild-type secretory protein, apolipoprotein B100 (apoB), to the cytosol for ubiquitin-proteasome proteolysis has been observed in HepG2 cells. A currently accepted model for proteasomal degradation of secretory proteins is retrograde translocation of the substrate polypeptides from the lumen of endoplasmic reticulum (ER) back to the cytosol. In this report, we present evidence that newly synthesized apoB becomes exposed to the cytosol and targeted to the proteasomes in a co-translational manner. Thus, after protein translation was synchronized with puromycin, partially synthesized apoB polypeptides were found to be conjugated to ubiquitin. The magnitude of co-translationalubiquitination and subsequent degradation of apoB was increased when cells were pretreated with either herbimycin A to induce cytosolic Hsp70 or with an inhibitor of microsomal triglyceride transfer protein; both treatments impede translocation of nascent apoB across the ER membrane. These treatments also decreased secretion of apoB and increased its degradation via the ubiquitin-proteasome pathway. We suggest that translocation arrest with subsequent co-translational exposure to the cytosol provides an alternative model to explain how mammalian secretory proteins can overcome topological segregation by the ER membrane and undergo degradation by the ubiquitin-proteasome pathway.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 11/07/20 alle ore 21:09:26