scholarly journals The Signal Peptide of the Mouse Mammary Tumor Virus Rem Protein Is Released from the Endoplasmic Reticulum Membrane and Accumulates in Nucleoli

2008 ◽  
Vol 283 (15) ◽  
pp. 9966-9976 ◽  
Author(s):  
Elisa Dultz ◽  
Markus Hildenbeutel ◽  
Bruno Martoglio ◽  
Jacob Hochman ◽  
Bernhard Dobberstein ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Signal Peptide ◽  
Mammary Tumor ◽  
Mouse Mammary Tumor Virus ◽  
Endoplasmic Reticulum Membrane ◽  
Mammary Tumor Virus ◽  
Mouse Mammary Tumor ◽  
Tumor Virus

scholarly journals Requirements for Mouse Mammary Tumor Virus Rem Signal Peptide Processing and Function

2011 ◽  
Vol 86 (1) ◽  
pp. 214-225 ◽  
Author(s):  
H. Byun ◽  
N. Halani ◽  
Y. Gou ◽  
A. K. Nash ◽  
M. M. Lozano ◽  
...  
Keyword(s):  
Signal Peptide ◽  
Mammary Tumor ◽  
Mouse Mammary Tumor Virus ◽  
Mammary Tumor Virus ◽  
Peptide Processing ◽  
Mouse Mammary Tumor ◽  
Tumor Virus ◽  
And Function

The Signal Peptide of Mouse Mammary Tumor Virus-Env: A Phosphoprotein Tumor Modulator

2012 ◽  
Vol 10 (8) ◽  
pp. 1077-1086 ◽  
Author(s):  
Dafna Feldman ◽  
Maayan Roniger ◽  
Allan Bar-Sinai ◽  
Ori Braitbard ◽  
Carmit Natan ◽  
...  
Keyword(s):  
Signal Peptide ◽  
Mammary Tumor ◽  
Mouse Mammary Tumor Virus ◽  
Mammary Tumor Virus ◽  
Mouse Mammary Tumor ◽  
Tumor Virus

scholarly journals Mouse Mammary Tumor Virus Signal Peptide Uses a Novel p97-Dependent and Derlin-Independent Retrotranslocation Mechanism To Escape Proteasomal Degradation

mBio ◽  
2017 ◽  
Vol 8 (2) ◽  
Author(s):  
Hyewon Byun ◽  
Poulami Das ◽  
Houqing Yu ◽  
Alejandro Aleman ◽  
Mary M. Lozano ◽  
...  
Keyword(s):  
Signal Peptide ◽  
Mammary Tumor ◽  
Mouse Mammary Tumor Virus ◽  
Proteasomal Degradation ◽  
Membrane Extraction ◽  
Terminal Protein ◽  
Mammary Tumor Virus ◽  
Mouse Mammary Tumor ◽  
Tumor Virus ◽  
Er Membrane

ABSTRACT Multiple pathogens, including viruses and bacteria, manipulate endoplasmic reticulum-associated degradation (ERAD) to avoid the host immune response and promote their replication. The betaretrovirus mouse mammary tumor virus (MMTV) encodes Rem, which is a precursor protein that is cleaved into a 98-amino-acid signal peptide (SP) and a C-terminal protein (Rem-CT). SP uses retrotranslocation for ER membrane extraction and yet avoids ERAD by an unknown mechanism to enter the nucleus and function as a Rev-like protein. To determine how SP escapes ERAD, we used a ubiquitin-activated interaction trap (UBAIT) screen to trap and identify transient protein interactions with SP, including the ERAD-associated p97 ATPase, but not E3 ligases or Derlin proteins linked to retrotranslocation, polyubiquitylation, and proteasomal degradation of extracted proteins. A dominant negative p97 ATPase inhibited both Rem and SP function. Immunoprecipitation experiments indicated that Rem, but not SP, is polyubiquitylated. Using both yeast and mammalian expression systems, linkage of a ubiquitin-like domain (UbL) to SP or Rem induced degradation by the proteasome, whereas SP was stable in the absence of the UbL. ERAD-associated Derlin proteins were not required for SP activity. Together, these results suggested that Rem uses a novel p97-dependent, Derlin-independent retrotranslocation mechanism distinct from other pathogens to avoid SP ubiquitylation and proteasomal degradation. IMPORTANCE Bacterial and viral infections produce pathogen-specific proteins that interfere with host functions, including the immune response. Mouse mammary tumor virus (MMTV) is a model system for studies of human complex retroviruses, such as HIV-1, as well as cancer induction. We have shown that MMTV encodes a regulatory protein, Rem, which is cleaved into an N-terminal signal peptide (SP) and a C-terminal protein (Rem-CT) within the endoplasmic reticulum (ER) membrane. SP function requires ER membrane extraction by retrotranslocation, which is part of a protein quality control system known as ER-associated degradation (ERAD) that is essential to cellular health. Through poorly understood mechanisms, certain pathogen-derived proteins are retrotranslocated but not degraded. We demonstrate here that MMTV SP retrotranslocation from the ER membrane avoids degradation through a unique process involving interaction with cellular p97 ATPase and failure to acquire cellular proteasome-targeting sequences.

Electron Microscopy of the Nucleic Acid of Mouse Mammary Tumor Virus

1968 ◽  
Vol 26 ◽  
pp. 22-23
Author(s):  
N. H. Sarkar ◽  
Dan H. Moore
Keyword(s):  
Mammary Tumor ◽  
Mouse Mammary Tumor Virus ◽  
Ammonium Acetate ◽  
Dry Weight ◽  
Mouse Tumor ◽  
Mammary Tumor Virus ◽  
Rna Molecules ◽  
Mouse Mammary Tumor ◽  
Tumor Virus ◽  
The Subject

Mouse mammary tumor virus (MTV) is believed to contain about 0.8% single stranded ribonucleic acid (RNA). This value of RNA content was estimated on a dry weight basis. The subject of this report is an attempt to visualize the RNA molecules of MTV particles.MTV particles were isolated from RIII mouse (tumor incidence approximately 80%) milk according to the method described by Lyons and Moore. Purified virions from 5 ml of milk were finally suspended in 0.2 ml of PBS, pH 7.4 and was mixed with an equal volume of pronase (5 mg/ml). This mixture was incubated at 37°C for an hour. RNA was extracted three times using freshly prepared cold phenol. It was then treated three times with cold ethyl ether to remove any trace of phenol. The RNA thus extracted was divided into two parts. One part was diluted four fold with 8M urea to avoid aggregation of the molecules. The other part was left untreated. Both samples were then mixed with an equal volume of 1M ammonium acetate, adjusted to pH 8.0 with NH3 containing chymotrypsin at a concentration of 0.01%.

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