Preparing your results

Our searching services are busy right now. Your search will reload in five seconds.

X
Forgot Password

If you have forgotten your password you can enter your email here and get a temporary password sent to your email.

Regulated endoplasmic reticulum-associated degradation of a polytopic protein: p97 recruits proteasomes to Insig-1 before extraction from membranes.

http://www.ncbi.nlm.nih.gov/pubmed/19815544

Polytopic membrane proteins subjected to endoplasmic reticulum (ER)-associated degradation are extracted from membranes and targeted to proteasomes for destruction. The extraction mechanism is poorly understood. One polytopic ER protein subjected to ER-associated degradation is Insig-1, a negative regulator of cholesterol synthesis. Insig-1 is rapidly degraded by proteasomes when cells are depleted of cholesterol, and its degradation is inhibited when sterols accumulate in cells. Insig-2, a functional homologue of Insig-1, is degraded slowly, and its degradation is not regulated by sterols. Here, we report that a single amino acid substitution in Insig-2, Insig-2(L210A), causes Insig-2 to be degraded in an accelerated and sterol-regulated manner similar to Insig-1. In seeking an explanation for the accelerated degradation, we found that proteasomes bind to wild type Insig-1 and mutant Insig-2(L210A) but not to wild type Insig-2, whereas the proteins are still embedded in cell membranes. This binding depends on at least two factors, ubiquitination of Insig and association with the ATPase p97/VCP complex. These data suggest that p97 recruits proteasomes to polytopic ER proteins even before they are extracted from membranes.

Pubmed ID: 19815544 RIS Download

Mesh terms: Adenosine Triphosphatases | Amino Acid Sequence | Amino Acid Substitution | Animals | Cell Line | Cell Membrane | Cholesterol | Endoplasmic Reticulum | Fatty Acids | Humans | Intracellular Signaling Peptides and Proteins | Membrane Proteins | Molecular Sequence Data | Nuclear Proteins | Proteasome Endopeptidase Complex | Protein Subunits | RNA Interference | Receptors, Autocrine Motility Factor | Receptors, Cytokine | Sequence Alignment | Ubiquitin-Protein Ligases | Ubiquitination

Research resources used in this publication

None found

Research tools detected in this publication

None found

Data used in this publication

None found

Associated grants

  • Agency: NHLBI NIH HHS, Id: 2P01HL20948
  • Agency: NIDDK NIH HHS, Id: R01DK46181

BioGRID (Data, Interactions)

Publication data is provided by the National Library of Medicine ® and PubMed ®. Data is retrieved from PubMed ® on a weekly schedule. For terms and conditions see the National Library of Medicine Terms and Conditions.