MafB, a new Maf family transcription activator that can associate with Maf and Fos but not with Jun

1994 ◽  
Vol 14 (11) ◽  
pp. 7581-7591
Author(s):  
K Kataoka ◽  
K T Fujiwara ◽  
M Noda ◽  
M Nishizawa
Keyword(s):  
Gene Overexpression ◽  
Transcription Activator ◽  
Repeat Structure ◽  
Bzip Domain ◽  
Carboxy Terminal Region ◽  
Recognition Elements ◽  
Carboxy Terminal ◽  
Related Proteins ◽  
Chicken Embryo Fibroblasts

We have identified a new member of the maf oncogene family and named it mafB. This gene is expressed in a wide variety of tissues and encodes a protein of 311 amino acids containing a typical bZip motif in its carboxy-terminal region. In the bZip domain, MafB shares extensive homology not only with v-Maf but also with other Maf-related proteins. As expected from its structure, MafB forms a homodimer through its leucine repeat structure and specifically binds Maf-recognition elements (MAREs). In addition, MafB forms heterodimers with v-Maf and Fos through its zipper structure. However, unlike v-Maf, MafB fails to associate with Jun. Transient cotransfection assays revealed that both v-Maf and MafB act as transactivators for a promoter linked to MAREs, although MafB is less potent than v-Maf. As is the case for the c-maf gene, overexpression of the mafB gene induces transformation of chicken embryo fibroblasts in vitro. Through formation of numerous bZip dimers, the Maf family proteins along with the AP-1 components should provide great diversity in transcriptional regulation for a wide variety of genes.

scholarly journals MafB, a new Maf family transcription activator that can associate with Maf and Fos but not with Jun.

1994 ◽  
Vol 14 (11) ◽  
pp. 7581-7591 ◽  
Author(s):  
K Kataoka ◽  
K T Fujiwara ◽  
M Noda ◽  
M Nishizawa
Keyword(s):  
Gene Overexpression ◽  
Transcription Activator ◽  
Repeat Structure ◽  
Bzip Domain ◽  
Carboxy Terminal Region ◽  
Recognition Elements ◽  
Carboxy Terminal ◽  
Related Proteins ◽  
Chicken Embryo Fibroblasts

We have identified a new member of the maf oncogene family and named it mafB. This gene is expressed in a wide variety of tissues and encodes a protein of 311 amino acids containing a typical bZip motif in its carboxy-terminal region. In the bZip domain, MafB shares extensive homology not only with v-Maf but also with other Maf-related proteins. As expected from its structure, MafB forms a homodimer through its leucine repeat structure and specifically binds Maf-recognition elements (MAREs). In addition, MafB forms heterodimers with v-Maf and Fos through its zipper structure. However, unlike v-Maf, MafB fails to associate with Jun. Transient cotransfection assays revealed that both v-Maf and MafB act as transactivators for a promoter linked to MAREs, although MafB is less potent than v-Maf. As is the case for the c-maf gene, overexpression of the mafB gene induces transformation of chicken embryo fibroblasts in vitro. Through formation of numerous bZip dimers, the Maf family proteins along with the AP-1 components should provide great diversity in transcriptional regulation for a wide variety of genes.

scholarly journals STAT5 and Oct-1 Form a Stable Complex That Modulates Cyclin D1 Expression

2003 ◽  
Vol 23 (24) ◽  
pp. 8934-8945 ◽  
Author(s):  
Sophie Magné ◽  
Sandrine Caron ◽  
Martine Charon ◽  
Marie-Christine Rouyez ◽  
Isabelle Dusanter-Fourt
Keyword(s):  
Cyclin D1 ◽  
Target Genes ◽  
Promoter Sequence ◽  
Stable Complex ◽  
Homeodomain Protein ◽  
Carboxy Terminal Region ◽  
Carboxy Terminal ◽  
Cell Cycle Regulator Cyclin

ABSTRACT Signal transducer and activator of transcription 5 (STAT5) is activated by numerous cytokines that control blood cell development. STAT5 was also shown to actively participate in leukemogenesis. Among the target genes involved in cell growth, STAT5 had been shown to activate cyclin D1 gene expression. We now show that thrombopoietin-dependent activation of the cyclin D1 promoter depends on the integrity of a new bipartite proximal element that specifically binds STAT5A and -B transcription factors. We demonstrate that the stable recruitment of STAT5 to this element in vitro requires the integrity of an adjacent octamer element that constitutively binds the ubiquitous POU homeodomain protein Oct-1. We observe that cytokine-activated STAT5 and Oct-1 form a unique complex with the cyclin D1 promoter sequence. We find that STAT5 interacts with Oct-1 in vivo, following activation by different cytokines in various cellular contexts. This interaction involves a small motif in the carboxy-terminal region of STAT5 which, remarkably, is similar to an Oct-1 POU-interacting motif present in two well-known partners of Oct-1, namely, OBF-1/Bob and SNAP190. Our data offer new insights into the transcriptional regulation of the key cell cycle regulator cyclin D1 and emphasize the active roles of both STAT5 and Oct-1 in this process.

STUDIES ON A HUMAN CHORIONIC GONADOTROPHIN-LIKE MATERIAL PRESENT IN NON-PREGNANT SUBJECTS

1978 ◽  
Vol 89 (3) ◽  
pp. 492-505 ◽  
Author(s):  
D. M. Robertson ◽  
H. Suginami ◽  
H. Hernandez Montes ◽  
C. P. Puri ◽  
S. K. Choi ◽  
...  
Keyword(s):  
Gel Filtration ◽  
Chorionic Gonadotrophin ◽  
Human Chorionic Gonadotrophin ◽  
Specific Sequence ◽  
Gonadotrophin Secretion ◽  
Carboxy Terminal Region ◽  
Assay Methods ◽  
Low Levels ◽  
Carboxy Terminal

ABSTRACT The presence of an hCG-like material in urinary and pituitary extracts and plasma obtained from non-pregnant subjects was investigated. Two assay methods were used to detect this material following fractionation of pituitary and urinary extracts by gel filtration (Ultrogel AcA 54) and/or isoelectrofocusing: a) a radioimmunoassay employing an antiserum raised against a specific sequence of the carboxy terminal region (residues 115– 145) of the β-subunit of hCG, and b) an in vitro bioassay method which measures both hLH and hCG activities. The fractionation procedures employed provide a satisfactory separation of highly purified hCG and hLH preparations. In the pituitary and urinary extracts hCGβ-peptide-like immunoactive (PIA) material was found consistently, which co-eluted with iodinated hCG following gel filtration and possessed pI values similar to those of hCG when subjected to isoelectrofocusing. The PIA material also exhibited in vitro biological activity similar to that shown by hLH and hCG. Detectable levels of immunoactive material were also found in plasma; however, the plasma levels of this PIA material were not influenced by classical endocrine measures such as the stimulation or inhibition of gonadotrophin secretion. The low levels of this material in plasma precluded its further characterization by gel filtration or electrofocusing. Whereas the present data and those reported by other investigators seem to suggest the presence of some hCG-like material in urinary and pituitary extracts and possibly in plasma of non-pregnant subjects, it is emphasized that the available evidence is not sufficiently conclusive to exclude other interpretations as to the nature of this material.

scholarly journals Negative Regulation of DNA Replication by the Retinoblastoma Protein Is Mediated by Its Association with MCM7

1998 ◽  
Vol 18 (5) ◽  
pp. 2748-2757 ◽  
Author(s):  
Jacqueline M. Sterner ◽  
Susan Dew-Knight ◽  
Christine Musahl ◽  
Sally Kornbluth ◽  
Jonathan M. Horowitz
Keyword(s):  
Amino Acids ◽  
Dna Replication ◽  
Protein Complexes ◽  
Replication Assay ◽  
Amino Terminal ◽  
Licensing Factor ◽  
Human Proteins ◽  
Carboxy Terminal ◽  
Related Proteins

ABSTRACT A yeast two-hybrid screen was employed to identify human proteins that specifically bind the amino-terminal 400 amino acids of the retinoblastoma (Rb) protein. Two independent cDNAs resulting from this screen were found to encode the carboxy-terminal 137 amino acids of MCM7, a member of a family of proteins that comprise replication licensing factor. Full-length Rb and MCM7 form protein complexes in vitro, and the amino termini of two Rb-related proteins, p107 and p130, also bind MCM7. Protein complexes between Rb and MCM7 were also detected in anti-Rb immunoprecipitates prepared from human cells. The amino-termini of Rb and p130 strongly inhibited DNA replication in an MCM7-dependent fashion in a Xenopus in vitro DNA replication assay system. These data provide the first evidence that Rb and Rb-related proteins can directly regulate DNA replication and that components of licensing factor are targets of the products of tumor suppressor genes.

Aberrant dimerization of von Willebrand factor as the result of mutations in the carboxy-terminal region: identification of 3 mutations in members of 3 different families with type 2A (phenotype IID) von Willebrand disease

Blood ◽  
2001 ◽  
Vol 98 (3) ◽  
pp. 674-680 ◽  
Author(s):  
M. Said Enayat ◽  
Andrea M. Guilliatt ◽  
Gurcharan K. Surdhar ◽  
P. Vincent Jenkins ◽  
K. John Pasi ◽  
...  
Keyword(s):  
Von Willebrand Factor ◽  
Von Willebrand Disease ◽  
Site Directed Mutagenesis ◽  
Direct Dna Sequencing ◽  
Mismatch Detection ◽  
Carboxy Terminal Region ◽  
Carboxy Terminal ◽  
Von Willebrand ◽  
Willebrand Factor

Abstract The 3′ end of the VWF gene was screened in the affected members of 3 different families with type 2A (phenotype IID) von Willebrand disease (vWD). Exons 49 to 52 of the VWF gene were amplified and screened for mutations by chemical cleavage mismatch detection. Mismatched bands were detected in exon 52 of 2 patients and in exon 51 of a third patient. Using direct DNA sequencing, a heterozygous G8562A transition leading to a Cys2008Tyr substitution was found in all the patients in family 1, and a T8561A transversion leading to a Cys2008Ser substitution was found in both patients from family 2. In a patient from a third family, an 8-base deletion from nucleotide 8437 to 8444 was identified in exon 51. The 2 mutations in exon 52 were reproduced by in vitro site-directed mutagenesis of full-length von Willebrand factor (vWF) cDNA and transiently expressed in COS-7 cells. The corresponding recombinant VWFs for these 2 mutations exhibited the typical aberrant vWF:Ag multimer pattern seen in the plasma of the patients. These 3 mutations demonstrate the importance of other carboxy-terminal cysteines in addition to the reported Cys2010 residue, in the normal dimerization of vWF, and their essential role in the assembly of normal multimeric vWF.

The carboxy-terminal region of mammalian HSP90 is required for its dimerization and function in vivo

1994 ◽  
Vol 14 (2) ◽  
pp. 1459-1464
Author(s):  
Y Minami ◽  
Y Kimura ◽  
H Kawasaki ◽  
K Suzuki ◽  
I Yahara
Keyword(s):  
Amino Acid ◽  
Terminal Region ◽  
Full Length ◽  
Yeast Cells ◽  
Amino Acid Residues ◽  
Haploid Strain ◽  
Carboxy Terminal Region ◽  
Carboxy Terminal ◽  
Hsp90 Alpha

The majority of mouse HSP90 exists as alpha-alpha and beta-beta homodimers. Truncation of the 15-kDa carboxy-terminal region of mouse HSP90 by digestion with the Ca(2+)-dependent protease m-calpain caused dissociation of the dimer. When expressed in a reticulocyte lysate, the full-length human HSP90 alpha formed a dimeric form. A plasmid harboring human HSP90 alpha cDNA was constructed so that the carboxy-terminal 49 amino acid residues were removed when translated in vitro. This carboxy-terminally truncated human HSP90 alpha was found to exist as a monomer. In contrast, loss of the 118 amino acid residues from the amino terminus of human HSP90 alpha did not affect its in vitro dimerization. Introduction of an expression plasmid harboring the full-length human HSP90 alpha complements the lethality caused by the double mutations of two HSP90-related genes, hsp82 and hsc82, in a haploid strain of Saccharomyces cerevisiae. The carboxy-terminally truncated human HSP90 alpha neither formed dimers in yeast cells nor rescued the lethal double mutant.

Identification of a novel dimer stabilization region in a plant bZIP transcription activator

1992 ◽  
Vol 12 (11) ◽  
pp. 4809-4816
Author(s):  
F Katagiri ◽  
K Seipel ◽  
N H Chua
Keyword(s):  
Dna Binding ◽  
Binding Affinity ◽  
Binding Proteins ◽  
Leucine Zipper ◽  
Dna Binding Proteins ◽  
Transcription Activator ◽  
Bzip Domain ◽  
Dna Binding Affinity ◽  
Necessary And Sufficient

We have carried out deletion analyses of a tobacco transcription activator, TGA1a, in order to define its functional domains. TGA1a belongs to the basic-region-leucine zipper (bZIP) class of DNA-binding proteins. Like other proteins of this class, it binds to its target DNA as a dimer, and its bZIP domain is necessary and sufficient for specific DNA binding. A mutant polypeptide containing the bZIP domain alone, however, shows a lower DNA-binding affinity than the full-length TGA1a. The C-terminal portion of TGA1a, which is essential for the higher DNA-binding affinity, contains a polypeptide region that can stabilize dimeric forms of the protein. This polypeptide region is designated the dimer stabilization (DS) region. Under our in vitro conditions, TGA1a derivatives with the DS region and those without the region do not form a detectable mixed dimer. This result indicates that in addition to the leucine zipper, the DS region can serve as another determinant of the dimerization specificity of TGA1a. In fact, the DS region, when fused to another bZIP protein, C/EBP, can inhibit dimer formation between the fusion protein and native C/EBP, whereas each of these can form homodimers. Such a portable determinant of dimerization specificity has potential application in studies of DNA-binding proteins as well as in biotechnology.

In vitro phosphorylation of the erythropoietin receptor and an associated protein, pp130

1992 ◽  
Vol 12 (2) ◽  
pp. 706-715
Author(s):  
A Yoshimura ◽  
H F Lodish
Keyword(s):  
Protein Kinase ◽  
Cell Surface ◽  
Terminal Region ◽  
Erythropoietin Receptor ◽  
Protein Kinase Activity ◽  
Carboxy Terminal Region ◽  
Cross Linker ◽  
Carboxy Terminal ◽  
A Site

The cytoplasmic domain of the cloned erythropoietin (EPO) receptor (EPOR) contains no protein kinase motif, yet addition of EPO to EPO-responsive cells causes an increase in protein-tyrosine phosphorylation. Here we show that addition of EPO or interleukin-3 (IL-3) to an IL-3-dependent cell line expressing the wild-type EPOR causes a small fraction (less than 5%) of total cellular EPOR to shift in gel mobility from 66 to 72 kDa, due at least in part to phosphorylation. Using biotinylated EPO as an affinity reagent, we show that the 72-kDa species is greatly enriched on the cell surface. To demonstrate that a protein kinase activity associates with cell surface EPOR, cells were incubated with biotinylated EPO and then cross-linked with a thiol-cleavable chemical cross-linker. The avidin-agarose-selected complexes were incubated with [gamma-32P]ATP. After in vitro phosphorylation and denaturation without reducing agent, both antiphosphotyrosine and anti-EPOR antibodies immunoprecipitated labeled 72-kDa EPOR and an unidentified 130-kDa phosphoprotein (pp130), indicating that a protein kinase is associated with cell surface EPOR and that a fraction of the EPOR was phosphorylated on tyrosine residues either in the cells or during the cell-free phosphorylation reaction. Under reducing conditions, the 72-kDa phosphorylated EPOR but not pp130 was immunoprecipitated with an anti-EPOR antibody, suggesting that the pp130 is bound to the EPOR by the thiol-cleavable chemical cross-linker. Previously, we showed that deletion of the 42 carboxy-terminal amino acids of the EPOR allows cells to grow in 1/10 the normal EPO concentration, without affecting receptor number or affinity. Two carboxy-terminal truncated EPO receptors that are hyperresponsive to EPO were poorly phosphorylated during the in vitro reaction, suggesting that the carboxy-terminal region of the EPOR contains a site for phosphorylation or a site for interaction with a protein kinase. Our data suggests that phosphorylation or interaction with a protein kinase in the carboxy-terminal region may down-modulate the proliferative action of the EPOR.

scholarly journals The carboxy-terminal region of mammalian HSP90 is required for its dimerization and function in vivo.

1994 ◽  
Vol 14 (2) ◽  
pp. 1459-1464 ◽  
Author(s):  
Y Minami ◽  
Y Kimura ◽  
H Kawasaki ◽  
K Suzuki ◽  
I Yahara
Keyword(s):  
Amino Acid ◽  
Terminal Region ◽  
Full Length ◽  
Yeast Cells ◽  
Amino Acid Residues ◽  
Haploid Strain ◽  
Carboxy Terminal Region ◽  
Carboxy Terminal ◽  
Hsp90 Alpha

The majority of mouse HSP90 exists as alpha-alpha and beta-beta homodimers. Truncation of the 15-kDa carboxy-terminal region of mouse HSP90 by digestion with the Ca(2+)-dependent protease m-calpain caused dissociation of the dimer. When expressed in a reticulocyte lysate, the full-length human HSP90 alpha formed a dimeric form. A plasmid harboring human HSP90 alpha cDNA was constructed so that the carboxy-terminal 49 amino acid residues were removed when translated in vitro. This carboxy-terminally truncated human HSP90 alpha was found to exist as a monomer. In contrast, loss of the 118 amino acid residues from the amino terminus of human HSP90 alpha did not affect its in vitro dimerization. Introduction of an expression plasmid harboring the full-length human HSP90 alpha complements the lethality caused by the double mutations of two HSP90-related genes, hsp82 and hsc82, in a haploid strain of Saccharomyces cerevisiae. The carboxy-terminally truncated human HSP90 alpha neither formed dimers in yeast cells nor rescued the lethal double mutant.

scholarly journals In vitro phosphorylation of the erythropoietin receptor and an associated protein, pp130.

1992 ◽  
Vol 12 (2) ◽  
pp. 706-715 ◽  
Author(s):  
A Yoshimura ◽  
H F Lodish
Keyword(s):  
Protein Kinase ◽  
Cell Surface ◽  
Terminal Region ◽  
Erythropoietin Receptor ◽  
Protein Kinase Activity ◽  
Carboxy Terminal Region ◽  
Cross Linker ◽  
Carboxy Terminal ◽  
A Site

The cytoplasmic domain of the cloned erythropoietin (EPO) receptor (EPOR) contains no protein kinase motif, yet addition of EPO to EPO-responsive cells causes an increase in protein-tyrosine phosphorylation. Here we show that addition of EPO or interleukin-3 (IL-3) to an IL-3-dependent cell line expressing the wild-type EPOR causes a small fraction (less than 5%) of total cellular EPOR to shift in gel mobility from 66 to 72 kDa, due at least in part to phosphorylation. Using biotinylated EPO as an affinity reagent, we show that the 72-kDa species is greatly enriched on the cell surface. To demonstrate that a protein kinase activity associates with cell surface EPOR, cells were incubated with biotinylated EPO and then cross-linked with a thiol-cleavable chemical cross-linker. The avidin-agarose-selected complexes were incubated with [gamma-32P]ATP. After in vitro phosphorylation and denaturation without reducing agent, both antiphosphotyrosine and anti-EPOR antibodies immunoprecipitated labeled 72-kDa EPOR and an unidentified 130-kDa phosphoprotein (pp130), indicating that a protein kinase is associated with cell surface EPOR and that a fraction of the EPOR was phosphorylated on tyrosine residues either in the cells or during the cell-free phosphorylation reaction. Under reducing conditions, the 72-kDa phosphorylated EPOR but not pp130 was immunoprecipitated with an anti-EPOR antibody, suggesting that the pp130 is bound to the EPOR by the thiol-cleavable chemical cross-linker. Previously, we showed that deletion of the 42 carboxy-terminal amino acids of the EPOR allows cells to grow in 1/10 the normal EPO concentration, without affecting receptor number or affinity. Two carboxy-terminal truncated EPO receptors that are hyperresponsive to EPO were poorly phosphorylated during the in vitro reaction, suggesting that the carboxy-terminal region of the EPOR contains a site for phosphorylation or a site for interaction with a protein kinase. Our data suggests that phosphorylation or interaction with a protein kinase in the carboxy-terminal region may down-modulate the proliferative action of the EPOR.

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