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Antigen-Antibody Complex definition: The complex formed by the binding of antigen and antibody molecules. The deposition of large antigen-antibody complexes leading to tissue damage causes IMMUNE COMPLEX DISEASES.
immune complex definition: product of an antigen antibody reaction; may also contain complement.
hydrogen transporting ATP synthase definition: two domain protein (F1 and F0) of inner mitochondrial membrane which couples electron transport to ATP synthesis via the proton gradient across the membrane when uncoupled, the reverse (ATPase) reaction drives a proton pump.
Proton-Translocating ATPases definition: Multisubunit enzymes that reversibly synthesize ADENOSINE TRIPHOSPHATE. They are coupled to the transport of protons across a membrane.
Multienzyme Complexes definition: Systems of enzymes which function sequentially by catalyzing consecutive reactions linked by common metabolic intermediates. They may involve simply a transfer of water molecules or hydrogen atoms and may be associated with large supramolecular structures such as MITOCHONDRIA or RIBOSOMES.
enzyme complex definition: systems of enzymes which function sequentially by catalyzing consecutive reactions linked by common metabolic intermediates; may involve simply a transfer of water molecules of hydrogen atoms or be associated with large supramolecular structures such as mitochondria or ribosomes.
Atrial Premature Complexes definition: A type of cardiac arrhythmia with premature atrial contractions or beats caused by signals originating from ectopic atrial sites. The ectopic signals may or may not conduct to the HEART VENTRICLES. Atrial premature complexes are characterized by premature P waves on ECG which are different in configuration from the P waves generated by the normal pacemaker complex in the SINOATRIAL NODE.
Atrial Premature Complex definition: Ectopic impulses originating in the atria.
PREMATURE ATRIAL COMPLEXES definition: Ectopic impulses originating in the atria. (NCI)
Myoelectric Complex, Migrating definition: A pattern of gastrointestinal muscle contraction and depolarizing myoelectric activity that moves from the stomach to the ILEOCECAL VALVE at regular frequency during the interdigestive period. The complex and its accompanying motor activity periodically cleanse the bowel of interdigestive secretion and debris in preparation for the next meal.
Photosynthetic Reaction Center, Bacterial definition: A system consisting of proteins and cofactors which acts as a light-driven electron pump across the photosynthetic membrane of photosynthetic bacteria.
Photosynthetic Reaction Center, Plant definition: A system consisting of proteins and cofactors which facilitates light energy and electron transfer in plants.
ISCOMs definition: A formulation for presenting an antigen to induce specific immunologic responses. It consists of an assembly of antigens in multimeric form. The assembly is attached to a matrix with a built-in adjuvant, saponin. ISCOMs induce strong serum antibody responses, and are used as highly immunogenic forms of subunit vaccines.
ATP Synthetase Complexes definition: Multisubunit enzyme complexes that synthesize ADENOSINE TRIPHOSPHATE from energy sources such as ions traveling through channels.
Ventricular Premature Complexes definition: A type of cardiac arrhythmia with premature contractions of the HEART VENTRICLES. It is characterized by the premature QRS complex on ECG that is of abnormal shape and great duration (generally >129 msec). It is the most common form of all cardiac arrhythmias. Premature ventricular complexes have no clinical significance except in concurrence with heart diseases.
premature ventricular contraction definition: premature ventricular beats, the most common of all arrhythmias; in the absence of heart disease, they are not of great clinical significance, but in patients with coronary disease, they represent a constant danger of ventricular tachycardia or fibrillation and sudden death.
Ventricular Premature Complex definition: Ectopic impulses originating in the ventricles.
PREMATURE VENTRICULAR COMPLEX definition: Ectopic impulses originating in the ventricles. (NCI)
Cardiac Complexes, Premature definition: A group of cardiac arrhythmias in which the cardiac contractions are not initiated at the SINOATRIAL NODE. They include both atrial and ventricular premature beats, and are also known as extra or ectopic heartbeats. Their frequency is increased in heart diseases.
Coordination Complexes definition: Neutral or negatively charged ligands bonded to metal cations or neutral atoms. The number of ligand atoms to which the metal center is directly bonded is the metal cation's coordination number, and this number is always greater than the regular valence or oxidation number of the metal. A coordination complex can be negative, neutral, or positively charged.
Multiprotein Complexes definition: Macromolecular complexes formed from the association of defined protein subunits.
histone deacetylase complex definition: A protein complex that possesses histone deacetylase activity. [GOC:mah]
Ubiquitin-Protein Ligase Complexes definition: Complexes of enzymes that catalyze the covalent attachment of UBIQUITIN to other proteins by forming a peptide bond between the C-terminal GLYCINE of UBIQUITIN and the alpha-amino groups of LYSINE residues in the protein. The complexes play an important role in mediating the selective-degradation of short-lived and abnormal proteins. The complex of enzymes can be broken down into three components that involve activation of ubiquitin (UBIQUITIN-ACTIVATING ENZYMES), conjugation of ubiquitin to the ligase complex (UBIQUITIN-CONJUGATING ENZYMES), and ligation of ubiquitin to the substrate protein (UBIQUITIN-PROTEIN LIGASES).
Ubiquitin Protein Ligase definition: Ubiquitin protein ligase enzymes catalyze the formation of a covalent peptide bond between the carboxy-terminal glycine of ubiquitin proteins and lysine alpha-amino group of other proteins. This typically marks proteins for either nonlysosomal proteasomal degradation or targeted transport. Ubiquitination requires sequential action of an activating enzyme, a conjugating enzyme, and a ligase.
Light-Harvesting Protein Complexes definition: Complexes containing CHLOROPHYLL and other photosensitive molecules. They serve to capture energy in the form of PHOTONS are generally found as components of the PHOTOSYSTEM I PROTEIN COMPLEX or the PHOTOSYSTEM II PROTEIN COMPLEX.
Adaptor Protein Complexes, Vesicular Transport definition: Multisubunit protein complexes of adaptor proteins.
Macromolecular Substances definition: Compounds and molecular complexes that consist of very large numbers of atoms and are generally over 500 kD in size. In biological systems macromolecular substances usually can be visualized using ELECTRON MICROSCOPY and are distinguished from ORGANELLES by the lack of a membrane structure.
Complex definition: A molecular entity formed by loose association involving two or more component molecular entities. The bonding between the components is normally weaker than in a covalent bond.
Endosomal Sorting Complexes Required for Transport definition: A set of protein subcomplexes involved in PROTEIN SORTING of UBIQUITINATED PROTEINS into intraluminal vesicles of MULTIVESICULAR BODIES and in membrane scission during formation of intraluminal vesicles, during the final step of CYTOKINESIS, and during the budding of enveloped viruses. The ESCRT machinery is comprised of the protein products of Class E vacuolar protein sorting genes.