scholarly journals Structural analysis of a mouse mammary tumor virus superantigen.

1992 ◽  
Vol 175 (3) ◽  
pp. 847-852 ◽  
Author(s):  
Y Choi ◽  
P Marrack ◽  
J W Kappler
Keyword(s):  
Amino Acids ◽  
T Cells ◽  
Mammary Tumor ◽  
Integral Membrane Protein ◽  
Open Reading Frames ◽  
In Vitro Translation ◽  
Type Ii ◽  
Long Terminal Repeats ◽  
Mouse Mammary Tumor

It has recently been shown that the minor lymphocyte stimulating-like products expressed by some mice are actually encoded by open reading frames in the 3' long terminal repeats of mouse mammary tumor viruses. These products act as viral superantigens (vSAGs). That is, they stimulate most T cells bearing particular V beta s almost regardless of the rest of the variable components of the T cell receptors expressed by those cells. To find out more about the structure of these vSAGs, a set of truncated vSAG genes was used in transfection and in vitro translation experiments to show that the functional vSAG is a type II integral membrane protein with a large glycosylated extracellular COOH-terminal domain and a small, nonessential, intracellular NH2-terminal cytoplasmic domain. These results are consistent with the fact that the vSAGs must be expressed on the cell surface in order to interact with T cells and class II major histocompatibility complex proteins. They also account for the finding that much of the V beta specificity of the vSAGs is controlled by amino acids at the COOH-terminal end of the vSAG proteins, amino acids that will be extracellular in type II proteins.

scholarly journals Direct evidence for the role of COOH terminus of mouse mammary tumor virus superantigen in determining T cell receptor V beta specificity.

1993 ◽  
Vol 178 (2) ◽  
pp. 737-741 ◽  
Author(s):  
K Yazdanbakhsh ◽  
C G Park ◽  
G M Winslow ◽  
Y Choi
Keyword(s):  
T Cell ◽  
Mammary Tumor ◽  
Transmembrane Domain ◽  
Cell Receptor ◽  
Integral Membrane Protein ◽  
Lysine Residue ◽  
Open Reading Frames ◽  
Long Terminal Repeats ◽  
Mouse Mammary Tumor ◽  
Tumor Virus

It has recently been shown that open reading frames in the 3' long terminal repeats of mouse mammary tumor viruses encode superantigens. These viral superantigens (vSAGs) stimulate most T cells expressing appropriate V beta s almost regardless of the rest of the variable components of the T cell receptors (TCR) expressed by those cells. vSAGs produce a type II integral membrane protein with a nonessential short cytoplasmic domain and a large glycosylated extracellular COOH-terminal domain, which is predicted to interact with major histocompatibility complex class II molecules and the TCR. The transmembrane region of vSAG also has an internal positively charged lysine residue of unknown significance. A set of chimeric and mutant vSAG genes has been used in transfection experiments to show that only the extreme COOH-terminal portion of vSAGs determine their TCR V beta specificities, and to show that the lysine residue in the transmembrane domain is not essential for the function of vSAG.

scholarly journals Translational and Structural Requirements of the Early Nodulin Gene enod40, a Short-Open Reading Frame-Containing RNA, for Elicitation of a Cell-Specific Growth Response in the Alfalfa Root Cortex

2001 ◽  
Vol 21 (1) ◽  
pp. 354-366 ◽  
Author(s):  
Carolina Sousa ◽  
Christina Johansson ◽  
Celine Charon ◽  
Hamid Manyani ◽  
Christof Sautter ◽  
...  
Keyword(s):  
Amino Acids ◽  
Biological Activity ◽  
Rna Structure ◽  
Open Reading Frames ◽  
In Vitro Translation ◽  
Cortical Cells ◽  
Root Cortex ◽  
Reading Frame ◽  
Early Nodulin

ABSTRACT A diversity of mRNAs containing only short open reading frames (sORF-RNAs; encoding less than 30 amino acids) have been shown to be induced in growth and differentiation processes. The early nodulin geneenod40, coding for a 0.7-kb sORF-RNA, is expressed in the nodule primordium developing in the root cortex of leguminous plants after infection by symbiotic bacteria. Ballistic microtargeting of this gene into Medicago roots induced division of cortical cells. Translation of two sORFs (I and II, 13 and 27 amino acids, respectively) present in the conserved 5′ and 3′ regions ofenod40 was required for this biological activity. These sORFs may be translated in roots via a reinitiation mechanism. In vitro translation products starting from the ATG of sORF I were detectable by mutating enod40 to yield peptides larger than 38 amino acids. Deletion of a Medicago truncatula enod40 region between the sORFs, spanning a predicted RNA structure, did not affect their translation but resulted in significantly decreased biological activity. Our data reveal a complex regulation of enod40action, pointing to a role of sORF-encoded peptides and structured RNA signals in developmental processes involving sORF-RNAs.

scholarly journals Characterization of kinectin, a kinesin-binding protein: primary sequence and N-terminal topogenic signal analysis.

1995 ◽  
Vol 6 (2) ◽  
pp. 171-183 ◽  
Author(s):  
H Yu ◽  
C V Nicchitta ◽  
J Kumar ◽  
M Becker ◽  
I Toyoshima ◽  
...  
Keyword(s):  
Amino Acids ◽  
Transmembrane Domain ◽  
Binding Protein ◽  
Coiled Coil ◽  
Integral Membrane Protein ◽  
In Vitro Translation ◽  
Predicted Amino Acid Sequence ◽  
Hydrophobic Region ◽  
Reading Frame

Kinectin is a kinesin-binding protein (Toyoshima et al., 1992) that is required for kinesin-based motility (Kumar et al., 1995). A kinectin cDNA clone containing a 4.7-kilobase insert was isolated from an embryonic chick brain cDNA library by immunoscreening with a panel of monoclonal antibodies. The cDNA contained an open reading frame of 1364 amino acids encoding a protein of 156 kDa. A bacterially expressed product of the full length cDNA bound purified kinesin. Transient expression in CV-1 cells gave an endoplasmic reticulum distribution that depended upon the N-terminal domain. Analysis of the predicted amino acid sequence indicated a highly hydrophobic near N-terminal stretch of 28 amino acids and a large portion (326-1248) of predicted alpha helical coiled coils. The 30-kDa fragment containing the N-terminal hydrophobic region was produced by cell-free in vitro translation and found to assemble with canine pancreas rough microsomes. Cleavage of the N terminus was not observed confirming its role as a potential transmembrane domain. Thus, the kinectin cDNA encodes a cytoplasmic-oriented integral membrane protein that binds kinesin and is likely to be a coiled-coil dimer.

scholarly journals An exogenous mouse mammary tumor virus with properties of Mls-1a (Mtv-7).

1992 ◽  
Vol 175 (6) ◽  
pp. 1623-1633 ◽  
Author(s):  
W Held ◽  
A N Shakhov ◽  
G Waanders ◽  
L Scarpellino ◽  
R Luethy ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Mammary Tumor ◽  
T Cell Response ◽  
T Cell Subsets ◽  
Clonal Deletion ◽  
Isolation And Characterization ◽  
Mouse Mammary Tumor

The classical minor lymphocyte stimulating (Mls) antigens, which induce a strong primary T cell response in vitro, are closely linked to endogenous copies of mouse mammary tumor viruses (MMTV). Expression of Mls genes leads to clonal deletion of T cell subsets expressing specific T cell receptor (TCR) V beta chains. We describe the isolation and characterization of a new exogenous (infectious) MMTV with biological properties similar to the Mls antigen Mls-1a. In vivo administration of either Mls-1a-expressing B cells or the infectious MMTV (SW) led to an increase of T cells expressing V beta 6 followed by their deletion. Surprisingly, different kinetics of deletion were observed with the exogenous virus depending upon the route of infection. Infection through the mucosa led to a slow deletion of V beta 6+ T cells, whereas deletion was rapid after subcutaneous infection. Sequence analysis of the open reading frames in the 3' long terminal repeat of both this exogenous MMTV (SW) and of Mtv-7 (which is closely linked to Mls-1a) revealed striking similarities, particularly in the COOH terminus, which has been implicated in TCR V beta recognition. The identification of an infectious MMTV with the properties of a strong Mls antigen provides a new, powerful tool to study immunity and tolerance in vivo.

scholarly journals The open reading frames in the 3' long terminal repeats of several mouse mammary tumor virus integrants encode V beta 3-specific superantigens.

1992 ◽  
Vol 175 (1) ◽  
pp. 41-47 ◽  
Author(s):  
A M Pullen ◽  
Y Choi ◽  
E Kushnir ◽  
J Kappler ◽  
P Marrack
Keyword(s):  
Mammary Tumor ◽  
Sequence Data ◽  
Cell Receptor ◽  
Open Reading Frames ◽  
Long Terminal Repeats ◽  
Tumor Viruses ◽  
Mouse Mammary Tumor ◽  
Tumor Virus ◽  
Terminal Repeats ◽  
Reading Frames

Mice expressing the minor lymphocyte stimulation antigens, Mls-1a, -2a, or -3a, singly on the B10.BR background have been generated. Mls phenotypes correlate with the integration of mouse mammary tumor viruses (MTV) in the mouse genome. The open reading frames within the 3' long terminal repeats of the integrated MTVs 1, 3, 6, and 13 encode V beta 3-specific superantigens. Sequence data for these viral superantigens is presented, indicating that it is the COOH-terminal portion of the viral superantigen that interacts with the T cell receptor V beta element.

Nucleosomes Reconstituted in Vitro on Mouse Mammary Tumor Virus B Region DNA Occupy Multiple Translational and Rotational Frames

Biochemistry ◽  
1995 ◽  
Vol 34 (38) ◽  
pp. 12470-12480 ◽  
Author(s):  
M. Scot Roberts ◽  
Gilberto Fragoso ◽  
Gordon L. Hager
Keyword(s):  
Mammary Tumor ◽  
Mouse Mammary Tumor Virus ◽  
Mammary Tumor Virus ◽  
Mouse Mammary Tumor ◽  
Tumor Virus

Rearrangements in the long terminal repeat of extra mouse mammary tumor proviruses in T-cell leukemias of mouse strain GR result in a novel enhancer-like structure

1985 ◽  
Vol 5 (4) ◽  
pp. 823-830
Author(s):  
R Michalides ◽  
E Wagenaar ◽  
P Weijers
Keyword(s):  
T Cell ◽  
Mammary Tumor ◽  
Low Frequency ◽  
T Cell Leukemia ◽  
Cell Leukemia ◽  
Long Terminal Repeats ◽  
Mammary Tumor Virus ◽  
Mouse Mammary Tumor ◽  
Tumor Virus ◽  
Tandem Repeat Region

Male GR mice develop T-cell leukemia at low frequency late in life. These leukemia cells invariably contain large amounts of mouse mammary tumor virus (MMTV) RNA and MMTV proteins and have extra MMTV proviruses integrated in their DNA. We show here that the extra MMTV proviruses are all derived from the endogenous MMTV provirus associated with the Mtv-2 locus and that the T-cell leukemias are clonal with respect to the acquired MMTV proviruses. The extra MMTV proviruses in six transplantable T-cell leukemia lines studied had rearranged, shortened long terminal repeats (LTRs); each T-cell leukemia, however, had a different LTR rearrangement within its extra MMTV provirus. The alteration within the extra LTRs of T-cell leukemia line 42 involved deletion of 453 nucleotides and generation of a tandem repeat region consisting of regions flanking the deletion. This alteration generated a sequence similar to the adenovirus enhancer core sequence. The viral RNAs in the T-cell leukemias contained corresponding alterations in their U3 regions. These results demonstrate that expression of MMTV in T-cell leukemias of GR mice may be the consequence of the generation of a novel enhancer, which could also stimulate expression of any adjacent cellular oncogene.

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