scholarly journals A specific protein substrate for a deubiquitinating enzyme: Liquid facets is the substrate of Fat facets

2002 ◽  
Vol 16 (3) ◽  
pp. 289-294 ◽  
Author(s):  
X. Chen
Keyword(s):  
Specific Protein ◽  
Deubiquitinating Enzyme ◽  
Protein Substrate ◽  
Fat Facets ◽  
Liquid Facets

scholarly journals The function of the Drosophila fat facets deubiquitinating enzyme in limiting photoreceptor cell number is intimately associated with endocytosis

Development ◽  
2000 ◽  
Vol 127 (8) ◽  
pp. 1727-1736 ◽  
Author(s):  
A.L. Cadavid ◽  
A. Ginzel ◽  
J.A. Fischer
Keyword(s):  
Compound Eye ◽  
Cell Communication ◽  
Photoreceptor Cells ◽  
Cell Number ◽  
Deubiquitinating Enzyme ◽  
A Cell ◽  
Fat Facets ◽  
Liquid Facets ◽  
And Function ◽  
Communication Pathway

Fat facets is a deubiquitinating enzyme required in a cell communication pathway that limits to eight the number of photoreceptor cells in each facet of the Drososphila compound eye. Genetic data support a model whereby Faf removes ubiquitin, a polypeptide tag for protein degradation, from a specific ubiquitinated protein thus preventing its degradation. Here, mutations in the liquid facets gene were identified as dominant enhancers of the fat facets mutant eye phenotype. The liquid facets locus encodes epsin, a vertebrate protein associated with the clathrin endocytosis complex. The results of genetic experiments reveal that fat facets and liquid facets facilitate endocytosis and function in common cells to generate an inhibitory signal that prevents ectopic photoreceptor determination. Moreover, it is demonstrated that the fat facets mutant phenotype is extraordinarily sensitive to the level of liquid facets expression. We propose that Liquid facets is a candidate for the critical substrate of Fat facets in the eye.

scholarly journals The Ras Target AF-6 is a Substrate of the Fam Deubiquitinating Enzyme

1998 ◽  
Vol 142 (4) ◽  
pp. 1053-1062 ◽  
Author(s):  
Shinichiro Taya ◽  
Takaharu Yamamoto ◽  
Kyoko Kano ◽  
Yoji Kawano ◽  
Akihiro Iwamatsu ◽  
...  
Keyword(s):  
Cell Fate ◽  
Plasma Membranes ◽  
Critical Role ◽  
Amino Acid Sequences ◽  
Cell Contact ◽  
Deubiquitinating Enzyme ◽  
Intact Cells ◽  
Cell Adhesions ◽  
Fat Facets ◽  
Cell Cell

The Ras target AF-6 has been shown to serve as one of the peripheral components of cell–cell adhesions, and is thought to participate in cell–cell adhesion regulation downstream of Ras. We here purified an AF-6-interacting protein with a molecular mass of ∼220 kD (p220) to investigate the function of AF-6 at cell–cell adhesions. The peptide sequences of p220 were identical to the amino acid sequences of mouse Fam. Fam is homologous to a deubiquitinating enzyme in Drosophila, the product of the fat facets gene. Recent genetic analyses indicate that the deubiquitinating activity of the fat facets product plays a critical role in controlling the cell fate. We found that Fam accumulated at the cell–cell contact sites of MDCKII cells, but not at free ends of plasma membranes. Fam was partially colocalized with AF-6 and interacted with AF-6 in vivo and in vitro. We also showed that AF-6 was ubiquitinated in intact cells, and that Fam prevented the ubiquitination of AF-6.

Control of Cell Fate by a Deubiquitinating Enzyme Encoded by the fat facets Gene

Science ◽  
1995 ◽  
Vol 270 (5243) ◽  
pp. 1828-1831 ◽  
Author(s):  
Y. Huang ◽  
R. T. Baker ◽  
J. A. Fischer-Vize
Keyword(s):  
Cell Fate ◽  
Deubiquitinating Enzyme ◽  
Fat Facets

scholarly journals In Vivo Structure/Function Analysis of the Drosophila fat facets Deubiquitinating Enzyme Gene

Genetics ◽  
2000 ◽  
Vol 156 (4) ◽  
pp. 1829-1836 ◽  
Author(s):  
Xin Chen ◽  
Janice A Fischer
Keyword(s):  
Amino Acid ◽  
Dna Sequences ◽  
Compound Eye ◽  
Function Analysis ◽  
P Element ◽  
Amino Acid Sequence Similarity ◽  
Deubiquitinating Enzyme ◽  
Specific Substrate ◽  
Deubiquitinating Enzymes ◽  
Fat Facets

Abstract The Drosophila Fat facets protein is a deubiquitinating enzyme required for patterning the developing compound eye. Ubiquitin, a 76-amino-acid polypeptide, serves as a tag to direct proteins to the proteasome, a protein degradation complex. Deubiquitinating enzymes are a large group of proteins that cleave ubiquitin-protein bonds. Fat facets belongs to a class of deubiquitinating enzymes called Ubps that share a conserved catalytic domain. Fat facets is unique among them in its large size and also because Fat facets is thought to deubiquitinate a specific substrate thereby preventing its proteolysis. Here we asked which portions of the Fat facets protein are essential for its function. P-element constructs that express partial Fat facets proteins were tested for function. In addition, the DNA sequences of 12 mutant fat facets alleles were determined. Finally, regions of amino acid sequence similarity in 18 Drosophila Ubps revealed by the Genome Project were identified. The results indicate functions for specific conserved amino acids in the catalytic region of Fat facets and also indicate that regions of the protein both N- and C-terminal to the catalytic region are required for Fat facets function.

On the conservation of function of the Drosophila Fat facets deubiquitinating enzyme and Fam, its mouse homolog

2000 ◽  
Vol 210 (12) ◽  
pp. 603-610 ◽  
Author(s):  
X. Chen ◽  
Erin Overstreet ◽  
Stephen A. Wood ◽  
J. A. Fischer
Keyword(s):  
Deubiquitinating Enzyme ◽  
Mouse Homolog ◽  
Fat Facets

Densitometric Identification of Primitive Erythroblasts After Reaction With Diaminobenzidine

1973 ◽  
Vol 31 ◽  
pp. 328-329
Author(s):  
John A. Trotter
Keyword(s):  
Red Blood Cells ◽  
Analytical Method ◽  
Blood Cells ◽  
Guinea Pigs ◽  
Specific Protein ◽  
Visual Examination ◽  
Hemoglobin Synthesis ◽  
Peroxidatic Activity ◽  
Small Density

Hemoglobin is the specific protein of red blood cells. Those cells in which hemoglobin synthesis is initiated are the earliest cells that can presently be considered to be committed to erythropoiesis. In order to identify such early cells electron microscopically, we have made use of the peroxidatic activity of hemoglobin by reacting the marrow of erythropoietically stimulated guinea pigs with diaminobenzidine (DAB). The reaction product appeared as a diffuse and amorphous electron opacity throughout the cytoplasm of reactive cells. The detection of small density increases of such a diffuse nature required an analytical method more sensitive and reliable than the visual examination of micrographs. A procedure was therefore devised for the evaluation of micrographs (negatives) with a densitometer (Weston Photographic Analyzer).

Specific Labeling of Protein Domains with Antibody Fragments

1981 ◽  
Vol 39 ◽  
pp. 416-417
Author(s):  
U. Aebi ◽  
L.E. Buhle ◽  
W.E. Fowler
Keyword(s):  
Image Processing ◽  
Specific Protein ◽  
Antibody Fragments ◽  
Supramolecular Organization ◽  
Two Dimensional ◽  
Ordered Structures ◽  
Virus Capsids ◽  
Processing Techniques

Many important supramolecular structures such as filaments, microtubules, virus capsids and certain membrane proteins and bacterial cell walls exist as ordered polymers or two-dimensional crystalline arrays in vivo. In several instances it has been possible to induce soluble proteins to form ordered polymers or two-dimensional crystalline arrays in vitro. In both cases a combination of electron microscopy of negatively stained specimens with analog or digital image processing techniques has proven extremely useful for elucidating the molecular and supramolecular organization of the constituent proteins. However from the reconstructed stain exclusion patterns it is often difficult to identify distinct stain excluding regions with specific protein subunits. To this end it has been demonstrated that in some cases this ambiguity can be resolved by a combination of stoichiometric labeling of the ordered structures with subunit-specific antibody fragments (e.g. Fab) and image processing of the electron micrographs recorded from labeled and unlabeled structures.

Immunocytochemical localization of p65 with one-nanometer gold particles following silver development

1989 ◽  
Vol 47 ◽  
pp. 1042-1043
Author(s):  
Richard W. Burry ◽  
Diane M. Hayes
Keyword(s):  
Plasma Membrane ◽  
Bovine Serum Albumin ◽  
Calf Serum ◽  
Specific Protein ◽  
Immunocytochemical Localization ◽  
Electron Microscopic ◽  
Gold Particles ◽  
Pass Through ◽  
Label Distribution ◽  
Phosphate Buffered Saline

Electron microscopic (EM) immunocytochemistry localization of the neuron specific protein p65 could show which organelles contain this antigen. Antibodies (Ab) labeled with horseradish peroxidase (HRP) followed by chromogen development show a broad diffuse label distribution within cells and restricting identification of organelles. Particulate label (e.g. 10 nm colloidal gold) is highly desirable but not practical because penetration into cells requires destroying the plasma membrane. We report pre-embedding immunocytochemistry with a particulate marker, 1 nm gold, that will pass through membranes treated with saponin, a mild detergent.Cell cultures of the rat cerebellum were fixed in buffered 4% paraformaldehyde and 0.1% glutaraldehyde (Glut.). The buffer for all incubations and rinses was phosphate buffered saline with: 1% calf serum, 0.2% saponin, 0.1% gelatin, 50 mM glycine 1 mg/ml bovine serum albumin, and (not in the HRP labeled cultures) 0.02% sodium azide. The monoclonal #48 to p65 was used with three label systems: HRP, 1 nm avidin gold with IntenSE M development, and 1 nm avidin gold with Danscher development.

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