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BIOL 201
NUHS PHYS CH5
Question | Answer |
---|---|
a specific protein in either the plasma membrane or the interior of a target cell that a chemical messenger combines within thereby invoking a biologically relevant response in that cell | Receptor (receptor protein) |
the ability of a receptor to bind only one type or a limited number of structurally related types of chemical messengers | Specificity |
the degree to which receptors are occupied by messengers. If all are occupied, the receptors are fully saturated; 100%, and so on | Saturation |
the strength with which a chemical messenger binds to its receptor | Affinity |
the ability of different molecules very similar in structure to compete with each other to combine with the same receptor | Competition |
a molecule that competes for a receptor with a chemical messenger normally present in the body. Binds to the receptor but does not trigger the cell's response. Ex; Antihistamines | Antagonist |
a chemical messenger that binds to a receptor and triggers the cell's response; often refers to a drug that mimics a normal messengers action. Ex: Decongestants | Agonist |
a decrease in the total number of target-cell receptors for a given messenger; may occur in response to chronic high extracellular concentration of the messenger | Down-regulation |
an increase in the total number of target-cell receptors for a given messenger; may occur in response to a chronic low extracellular concentration of the messenger. | Up-regulation |
the increased responsiveness of a target cell to a given messenger; may result from up-regulation of receptors | Supersensitivity |
change in receptor conformation caused by combination of messenger with receptor | Receptor activation |
any enzyme that phosphorylates other proteins by transferring a phosphate group to them from ATP | Protein Kinase |
sequence of mechanisms that relay information from plasma-membrane receptor to cell's response mechanism | Signal Transduction Pathway |
class of intracellular receptor proteins that bind steroid hormones and other lipophilic molecules and induce changes in gene transcription | Steroid Hormone Receptor Superfamily |
one of a class of proteins that act as gene switches, regulating the transcription of a particular gene by activating or repressing the initiation process | Transcription Factor |
membrane channel operated by the binding of specific molecules to channel proteins | Ligand-gated Channel |
the major type of receptor protein that is itself an enzyme; these receptors are on plasma membranes and respond to many different water-soluble chemical messengers | Receptor Tyrosine Kinase |
the intercellular chemical messengers that reach the cell from the extracellular fluid and bind to their specific plasma membrane receptors | First Messengers |
substances that enter or are generated in the cytoplasm as a result of receptor activation by the first messenger | Second Messengers |
cyclic nucleotide that acts as second messenger in some cells | cGMP |
enzyme that is activated by cyclic GMP, and then phosphorylates specific proteins, thereby altering their activity | cyclic GMP-dependent protein kinase |
one protein from a family of regulatory proteins that reversibly bind guanosine nucleotides; these interact with membrane ion channels or enzymes | G protein |
enzyme that catalyzes transformation of ATP to cyclic AMP (cAMP) | Adenylyl cyclase |
cyclic nucleotide that serves as a second messenger for many "first" chemical messengers | Cyclic AMP (cAMP) |
enzyme that catalyzes cyclic AMP breakdown to AMP | Phosphodiesterase |
enzyme that is activated by cyclic AMP and then phosphorylates specific proteins, thereby altering their activity | cAMP-dependent protein kinase |
second messenger that activates protein kinase C, which then phosphorylates a large number of other proteins | Diacylglycerol (DAG) |
second messenger that causes release of calcium from endoplasmic reticulum into cytosol | Inositol trisphosphate (IP3) |
enzyme that phosphorylates certain intracellular proteins when activated by diacylglycerol | Protein kinase C |
intracellular calcium-binding protein that mediates many of calcium's second-messenger functions | Calmodulin |
an intracellular enzyme that, when activated by calcium and the protein calmodulin, phosphorylates many protein substrates within cells; it is a component of many intracellular signaling mechanisms | Calmodulin-dependent protein kinase |