Sumoylation
A type of POST-TRANSLATIONAL PROTEIN MODIFICATION by SMALL UBIQUITIN-RELATED MODIFIER PROTEINS (also known as SUMO proteins).
Small Ubiquitin-Related Modifier Proteins
A class of structurally related proteins of 12-20 kDa in size. They covalently modify specific proteins in a manner analogous to UBIQUITIN.
SUMO-1 Protein
A 1.5-kDa small ubiquitin-related modifier protein that can covalently bind via an isopeptide link to a number of cellular proteins. It may play a role in intracellular protein transport and a number of other cellular processes.
Protein Inhibitors of Activated STAT
Ubiquitin-Conjugating Enzymes
A class of enzymes that form a thioester bond to UBIQUITIN with the assistance of UBIQUITIN-ACTIVATING ENZYMES. They transfer ubiquitin to the LYSINE of a substrate protein with the assistance of UBIQUITIN-PROTEIN LIGASES.
Protein Processing, Post-Translational
Any of various enzymatically catalyzed post-translational modifications of PEPTIDES or PROTEINS in the cell of origin. These modifications include carboxylation; HYDROXYLATION; ACETYLATION; PHOSPHORYLATION; METHYLATION; GLYCOSYLATION; ubiquitination; oxidation; proteolysis; and crosslinking and result in changes in molecular weight and electrophoretic motility.
Ubiquitin-Protein Ligases
A diverse class of enzymes that interact with UBIQUITIN-CONJUGATING ENZYMES and ubiquitination-specific protein substrates. Each member of this enzyme group has its own distinct specificity for a substrate and ubiquitin-conjugating enzyme. Ubiquitin-protein ligases exist as both monomeric proteins multiprotein complexes.
HEK293 Cells
A cell line generated from human embryonic kidney cells that were transformed with human adenovirus type 5.
Ubiquitins
A family of proteins that are structurally-related to Ubiquitin. Ubiquitins and ubiquitin-like proteins participate in diverse cellular functions, such as protein degradation and HEAT-SHOCK RESPONSE, by conjugation to other proteins.
Protein Binding
Intranuclear Inclusion Bodies
Circumscribed masses of foreign or metabolically inactive materials, within the CELL NUCLEUS. Some are VIRAL INCLUSION BODIES.
Ubiquitination
The act of ligating UBIQUITINS to PROTEINS to form ubiquitin-protein ligase complexes to label proteins for transport to the PROTEASOME ENDOPEPTIDASE COMPLEX where proteolysis occurs.
Ubiquitin
A highly conserved 76-amino acid peptide universally found in eukaryotic cells that functions as a marker for intracellular PROTEIN TRANSPORT and degradation. Ubiquitin becomes activated through a series of complicated steps and forms an isopeptide bond to lysine residues of specific proteins within the cell. These "ubiquitinated" proteins can be recognized and degraded by proteosomes or be transported to specific compartments within the cell.
COS Cells
CELL LINES derived from the CV-1 cell line by transformation with a replication origin defective mutant of SV40 VIRUS, which codes for wild type large T antigen (ANTIGENS, POLYOMAVIRUS TRANSFORMING). They are used for transfection and cloning. (The CV-1 cell line was derived from the kidney of an adult male African green monkey (CERCOPITHECUS AETHIOPS).)
Transcription, Genetic
Two-Hybrid System Techniques
Screening techniques first developed in yeast to identify genes encoding interacting proteins. Variations are used to evaluate interplay between proteins and other molecules. Two-hybrid techniques refer to analysis for protein-protein interactions, one-hybrid for DNA-protein interactions, three-hybrid interactions for RNA-protein interactions or ligand-based interactions. Reverse n-hybrid techniques refer to analysis for mutations or other small molecules that dissociate known interactions.
HeLa Cells
The first continuously cultured human malignant CELL LINE, derived from the cervical carcinoma of Henrietta Lacks. These cells are used for VIRUS CULTIVATION and antitumor drug screening assays.
Amino Acid Motifs
Ubiquitin-Activating Enzymes
A class of enzymes that catalyzes the ATP-dependent formation of a thioester bond between itself and UBIQUITIN. It then transfers the activated ubiquitin to one of the UBIQUITIN-PROTEIN LIGASES.
Repressor Proteins
Proteins which maintain the transcriptional quiescence of specific GENES or OPERONS. Classical repressor proteins are DNA-binding proteins that are normally bound to the OPERATOR REGION of an operon, or the ENHANCER SEQUENCES of a gene until a signal occurs that causes their release.
Cell Nucleus
Within a eukaryotic cell, a membrane-limited body which contains chromosomes and one or more nucleoli (CELL NUCLEOLUS). The nuclear membrane consists of a double unit-type membrane which is perforated by a number of pores; the outermost membrane is continuous with the ENDOPLASMIC RETICULUM. A cell may contain more than one nucleus. (From Singleton & Sainsbury, Dictionary of Microbiology and Molecular Biology, 2d ed)
Nuclear Proteins
Mutation
Amino Acid Sequence
Cercopithecus aethiops
Transcription Factors
RING Finger Domains
A zinc-binding domain defined by the sequence Cysteine-X2-Cysteine-X(9-39)-Cysteine-X(l-3)-His-X(2-3)-Cysteine-X2-Cysteine -X(4-48)-Cysteine-X2-Cysteine, where X is any amino acid. The RING finger motif binds two atoms of zinc, with each zinc atom ligated tetrahedrally by either four cysteines or three cysteines and a histidine. The motif also forms into a unitary structure with a central cross-brace region and is found in many proteins that are involved in protein-protein interactions. The acronym RING stands for Really Interesting New Gene.
Endopeptidases
Ligases
Protein Structure, Tertiary
The level of protein structure in which combinations of secondary protein structures (alpha helices, beta sheets, loop regions, and motifs) pack together to form folded shapes called domains. Disulfide bridges between cysteines in two different parts of the polypeptide chain along with other interactions between the chains play a role in the formation and stabilization of tertiary structure. Small proteins usually consist of only one domain but larger proteins may contain a number of domains connected by segments of polypeptide chain which lack regular secondary structure.
Immunoprecipitation
Molecular Sequence Data
Descriptions of specific amino acid, carbohydrate, or nucleotide sequences which have appeared in the published literature and/or are deposited in and maintained by databanks such as GENBANK, European Molecular Biology Laboratory (EMBL), National Biomedical Research Foundation (NBRF), or other sequence repositories.
Transcriptional Activation
Intranuclear Space
The area within the CELL NUCLEUS.
Histone Deacetylases
Deacetylases that remove N-acetyl groups from amino side chains of the amino acids of HISTONES. The enzyme family can be divided into at least three structurally-defined subclasses. Class I and class II deacetylases utilize a zinc-dependent mechanism. The sirtuin histone deacetylases belong to class III and are NAD-dependent enzymes.