Essential Cell Biology Chapter 4
Terms in this set (36)
Specialized region of an enzyme surface to which a substrate molecule binds before it undergoes a catalyzed reaction.
Describes a protein that can exist in two or more conformations depending on the binding of the molecule (a ligand) at a site other than the catalytic site. Allosteric proteins composed of multiple subunits often display a cooperative response to ligand binding, because the binding of a ligand to one subunit facilitates the binding of ligands to the other subunit.
Common structural motif of proteins in which a linear sequence of amino acids folds into a right-handed helix stabilized by internal hydrogen bonding between backbone atoms.
amino acid sequence
The order of amino acid residues in a protein chain. Sometimes called the primary structure of a protein.
Protein produced by B lymphocytes in response to a foreign molecule or invading organism. Binds to the foreign molecule or cell extremely tightly, thereby inactivating it or marking it for destruction.
Molecule that provokes the production of specific neutralizing antibodies in an immune response.
Folding pattern found in many proteins in which neighboring regions of the polypeptide chain associate side by side with each other through hydrogen bonds to give a rigid, flattened structure.
Region on the surface of a protein, typically a cavity or groove, that is complementary in shape to, and forms multiple noncovalent bonds with, a second molecule (the ligand).
A type of technique used to separate molecules in a mixture on the basis of their size, charge, or their ability to find a particular chemical group. In a common form of the technique, the mixture is run through a column filled with a particulate matrix that is designed to bind (or let through) the desired molecule.
Especially stable rod-like protein structure formed by two or more α helices coiled around each other.
Spatial location of the atoms of a molecule relative to each other. The precise shape of a protein or other macromolecule in three dimensions.
Covalent linkage formed between two sulfhydryl groups on cysteines. Common way to join two proteins or to link together different parts of the same protein in the extracellular space.
Technique for separating mixture of proteins of DNA fragments by size and electrical charge by placing them on a polymer gel and subjecting them to an electric field. The molecules migrate through the gel at different speeds depending on their size and net charge.
A form of metabolic control in which the end product of a chain of enzymatic reactions reduces the activity of an enzyme early in the pathway.
A protein with an elongated shape. Typically one such as collagen or intermediate filament protein that is able to associate into long filamentous structures.
Any protein with an approximately rounded shape. Most enzymes are globular.
An allosteric protein whose conformation and activity are determined by its association with either GTP or GDP. Includes many proteins involved in cell signaling, such as Ras and G proteins.
An elongated structure in which a filament or thread twists in a regular fashion around a central axis.
A molecule that binds to a specific site on a protein.
Protein such as myosin or kinesin that uses energy derived from ATP hydrolysis to propel itself along a protein filament or polymeric molecule.
nuclear magnetic resonance (NMR) spectroscopy
Technique used for determining the three-dimensional structure of a protein. It is performed in solution without requiring a protein crystal.
Linear polymer composed of multiple amino acids. Proteins are composed of one or more long polypeptide chains.
The chain of atoms containing repeating peptide bonds that runs through a protein molecule and to which the amino acid side chains are attached.
Small discrete region of a structure. A protein domain is a compact and stable folded region of polypeptide. A membrane domain is a region of bilayer with a characteristic lipid and protein composition.
A group of proteins in an organism with a similar amino acid sequence. The similarity is thought to reflect the evolution of the genes that encode the proteins from a common ancestor gene through a process of gene duplication followed by gene divergence. Usually, the different members of a protein family will have related but distinct functions. For example, each member of the protein kinase family carries out a similar phosphorylation reaction, but the substrates and regulation differ for each enzyme.
One of a very large number of enzymes that transfers the terminal phosphate group of ATP to a specific amino acid side chain on a target protein.
A set of protein molecules that bind to each other in specific ways, so that concerted movements within the protein complex can carry out a sequence of reactions with unusual speed and effectiveness. A large number of the central reactions of the cell are catalyzed by such protein machines, with protein synthesis and DNA replication being particularly well understood examples.
Enzyme that removes, by hydrolysis, a phosphate group from a protein, often with high specificity for the phosphorylated site.
The covalent addition of a phosphate group to a side chain of a protein catalyzed by a protein kinase. Phosphorylation usually alters the activity or properties of the protein in some way.
The large scale study of proteins, investigating many different proteins in a cell or tissue simultaneously.
regulatory protein code
The set of covalent modifications that a protein has at any given time, which controls the behavior of the protein inside the cell.
Regular local folding pattern of a polymeric molecule in proteins, it refers to α helices and β sheets.
Portion of an amino acid not involved in making peptide bonds; the side chain gives each amino acid its unique properties.
A monomer that forms part of a larger molecule, such as an amino acid residue in a protein or a nucleotide residue in a nucleic acid. Can also refer to a complete molecule that forms part of a larger molecule. Many proteins, for example, are composed of multiple polypeptide chains, each of which is called a protein subunit.
Chemical structure that forms transiently in the course of a reaction and has the highest free energy of any reaction intermediate.
Technique used to determine three-dimensional protein structures by analyzing the diffraction pattern of a beam of X-rays passed through a crystal of the protein.