scholarly journals Filamin A-Bound PEBP2β/CBFβ Is Retained in the Cytoplasm and Prevented from Functioning as a Partner of the Runx1 Transcription Factor

2005 ◽  
Vol 25 (3) ◽  
pp. 1003-1012 ◽  
Author(s):  
Naomi Yoshida ◽  
Takehiro Ogata ◽  
Kenji Tanabe ◽  
Songhua Li ◽  
Megumi Nakazato ◽  
...  

ABSTRACT The heterodimeric transcription factor PEBP2/CBF is composed of a DNA-binding subunit, called Runx1, and a non-DNA-binding subunit, called PEBP2β/CBFβ. The Runx1 protein is detected exclusively in the nuclei of most cells and tissues, whereas PEBP2β is located in the cytoplasm. We addressed the mechanism by which PEBP2β localizes to the cytoplasm and found that it is associated with filamin A, an actin-binding protein. Filamin A retains PEBP2β in the cytoplasm, thereby hindering its engagement as a Runx1 partner. The interaction with filamin A is mediated by a region within PEBP2β that includes amino acid residues 68 to 93. The deletion of this region or the repression of filamin A enables PEBP2β to translocate to the nucleus. Based on these observations, we propose that PEBP2β has two distinct domains, a newly defined regulatory domain that interacts with filamin A and the previously identified Runx1-binding domain.

2000 ◽  
Vol 301 (4) ◽  
pp. 807-816 ◽  
Author(s):  
Miguel Angel Garcı́a ◽  
Mónica Campillos ◽  
Samuel Ogueta ◽  
Fernando Valdivieso ◽  
Jesús Vázquez

1994 ◽  
Vol 14 (12) ◽  
pp. 7899-7908
Author(s):  
N Gerwin ◽  
A La Rosée ◽  
F Sauer ◽  
H P Halbritter ◽  
M Neumann ◽  
...  

The Drosophila gap gene knirps (kni) is required for abdominal segmentation. It encodes a steroid/thyroid orphan receptor-type transcription factor which is distributed in a broad band of nuclei in the posterior region of the blastoderm. To identify essential domains of the kni protein (KNI), we cloned and sequenced the DNA encompassing the coding region of nine kni mutant alleles of different strength and kni-homologous genes of related insect species. We also examined in vitro-modified versions of KNI in various assay systems both in vitro and in tissue culture. The results show that KNI contains several functional domains which are arranged in a modular fashion. The N-terminal 185-amino-acid region which includes the DNA-binding domain and a functional nuclear location signal fails to provide kni activity to the embryo. However, a truncated KNI protein that contains additional 47 amino acids exerts rather strong kni activity which is functionally defined by a weak kni mutant phenotype of the embryo. The additional 47-amino-acid stretch includes a transcriptional repressor domain which acts in the context of a heterologous DNA-binding domain of the yeast transcriptional activator GAL4. The different domains of KNI as defined by functional studies are conserved during insect evolution.


2002 ◽  
Vol 173 (3) ◽  
pp. 429-436 ◽  
Author(s):  
L Wickert ◽  
J Selbig

We have generated 24 DNA-binding domain structure models of alternatively spliced or mutated steroid receptor variants by homology-based modeling. Members of the steroid receptor family dispose of a DNA-binding domain which is built from two zinc fingers with a preserved sequence homology of about 90%. Data from crystallographic analysis of the glucocorticoid receptor DNA-binding domain are therefore appropriate to serve as a template structure. We inserted or deleted amino acid residues in order to study the structural details of the glucocorticoid, mineralocorticoid, and androgen receptor splice variants. The receptor variants are created by QUANTA- and MODELLER-based modeling. Subsequently, the resulting energy-minimized models were compared with each other and with the wild-type receptor respectively. A prediction for the receptor function based mainly on the preservation or destruction of secondary structures has been carried out. The simulations showed that amino acid insertions of one, four or nine additional residues of existing steroid receptor splice variants were tolerated without destruction of the secondary structure. In contrast, a deletion of four amino acids at the splice site junction leads to modifications in the secondary structure of the DNA-recognition helix which apparently disturb the receptor-DNA interaction. Furthermore, an insertion of 23 amino acid residues between the zinc finger of the androgen receptor leads to a large loop with an additional alpha-helical structure which seems to disconnect a specific contact from its hormone response element. Thereafter, the prediction of receptor function based on the molecular models was compared with the available experimental results from the in vitro function tests. We obtained a close correspondence between the molecular modeling-based predictions and the conclusions of receptor function drawn from in vitro studies.


1994 ◽  
Vol 14 (12) ◽  
pp. 7899-7908 ◽  
Author(s):  
N Gerwin ◽  
A La Rosée ◽  
F Sauer ◽  
H P Halbritter ◽  
M Neumann ◽  
...  

The Drosophila gap gene knirps (kni) is required for abdominal segmentation. It encodes a steroid/thyroid orphan receptor-type transcription factor which is distributed in a broad band of nuclei in the posterior region of the blastoderm. To identify essential domains of the kni protein (KNI), we cloned and sequenced the DNA encompassing the coding region of nine kni mutant alleles of different strength and kni-homologous genes of related insect species. We also examined in vitro-modified versions of KNI in various assay systems both in vitro and in tissue culture. The results show that KNI contains several functional domains which are arranged in a modular fashion. The N-terminal 185-amino-acid region which includes the DNA-binding domain and a functional nuclear location signal fails to provide kni activity to the embryo. However, a truncated KNI protein that contains additional 47 amino acids exerts rather strong kni activity which is functionally defined by a weak kni mutant phenotype of the embryo. The additional 47-amino-acid stretch includes a transcriptional repressor domain which acts in the context of a heterologous DNA-binding domain of the yeast transcriptional activator GAL4. The different domains of KNI as defined by functional studies are conserved during insect evolution.


1993 ◽  
Vol 13 (4) ◽  
pp. 2554-2563 ◽  
Author(s):  
D Wojciechowicz ◽  
C F Lu ◽  
J Kurjan ◽  
P N Lipke

alpha-Agglutinin is a cell adhesion glycoprotein expressed on the cell wall of Saccharomyces cerevisiae alpha cells. Binding of alpha-agglutinin to its ligand a-agglutinin, expressed by a cells, mediates cell-cell contact during mating. Analysis of truncations of the 650-amino-acid alpha-agglutinin structural gene AG alpha 1 delineated functional domains of alpha-agglutinin. Removal of the C-terminal hydrophobic sequence allowed efficient secretion of the protein and loss of cell surface attachment. This cell surface anchorage domain was necessary for linkage to a glycosyl phosphatidylinositol anchor. A construct expressing the N-terminal 350 amino acid residues retained full a-agglutinin-binding activity, localizing the binding domain to the N-terminal portion of alpha-agglutinin. A 278-residue N-terminal peptide was inactive; therefore, the binding domain includes residues between 278 and 350. The segment of alpha-agglutinin between amino acid residues 217 and 308 showed significant structural and sequence similarity to a consensus sequence for immunoglobulin superfamily variable-type domains. The similarity of the alpha-agglutinin-binding domain to mammalian cell adhesion proteins suggests that this structure is a highly conserved feature of adhesion proteins in diverse eukaryotes.


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