Terminology

Abscisic Acid - A sesquiterpene class of plant hormones derived from isopentenyl pyrophosphate
Adenylate Cyclase - A membrane-bound enzyme that catalyzes synthesis of cAMP in response to hormones, such as epinephrine or glucagon.
Adipocytes - Cells that are specialized for storing triacylglycerols and for releasing them to the blood in the form of fatty acids and glycerol as required. Figure 23.1
Adrenal Corticotropic Hormone (ACTH, also called -corticotropin) - A hormone secreted from the anterior pituitary that stimulates the adrenal coretx to produce glucocorticoids and mineralocortiocids, which in turn act on a number of tissues.
Adrenergic Receptors - Cell-surface receptors that bind epinephrine and norepinephrine. There are several different types with somewhat different ligand specificities and effects.
Agonist - A substance that mimics the cellular effects of a natural compound (such as a hormone or neurotransmitter) by binding to and activating the same cellular receptor.
Antagonist - A substance that counteracts the cellular effects of a natural compound (such as a hormone or neurotransmitter) by binding to the cellular receptor for the compound and blocking its action.
Atrial Natriuretic Factor - A protein which controls blood volume. It binds to a receptor that has both a guanylate cyclase activity and a predicted protein serine/threonine kinase activity.
Auxins - A class of plant hormones derived from tryptophan metabolism.
Catecholamines - A class of molecules, such as epinephrine, which are derived from tyrosine and contain a benzene ring with more than one hydroxyl group.
Cholera Toxin - A toxin of Vibrio cholerae that cleaves NAD+ and transfers its ADP-ribose moiety to a specific site in the subunit of Gs
Corticotropin Releasing Factor (CRF) - A 41-residue polypeptide released by the hypothalamus that stimulates the anterior pituitary to release ACTH.
CREB (Cyclic AMP Response Element Binding Protein) - A protein that cAMP binds to, which stimulates transcription of a class of genes, including cellular hormone receptor proteins.
Cytokinins - A class of plant hormones continine purine bases with a terpenoid side chain.
Diabetes Mellitus - A disease caused by a deficiency in the action of insulin in the body, resulting either from low insulin levels or from inadequate insulin levels combined with unresponsiveness of the target cells to insulin. The disease is manifested primarily by disturbances in fuel homeostasis, including hyperglycemia (abnormally high blood glucose levels).
Diethylstilbestrol - A synthetic estrogen that is more than 10 times more potent than natural estrogens.
Endocrine Glands - Cells that synthesize hormones and release them into the circulation.
Epinephrine - A compound which, when released from presynaptic nerve endings, acts as a neurotransmitter and, when released by the adrenal medulla, acts as a hormone to activate adenylate cyclase in increase cAMP levels in target cells.
Ethylene - A plant hormone which comes from the methionyl moiety of S-adenosylmethionine.
Exocrine Cells - A cell that secretes a substance that is excreted through a duct either into the alimentary tract or to the outside of the organism.
G Proteins - A class of proteins that transduce the signal received at the adrenergic receptor to adenylate cyclase, which they stimulate to catalyze synthesis of cAMP.
G i - A closely related family of G proteins involved in responses that inhibit adenylate cyclase.
Gibberellins - A diterpene class of plant hormones derived from isopentenyl pyrophosphate.
Glucagon - A 3.5 kD polypeptide synthesized by A cells of the islets of Langerhans in the pancreas. The hormone is released in response to low blood glucose levels. Figure 23.2
G s - A family of G proteins involved in stimulation of adenylate cyclase. Figure 23.12
Hormone Response Elements (HREs) - DNA sites that steroid hormone-hormone receptor complexes interact with in order to affect transcription of genes. Table 23.6
Hypothalamus - A specialized center of the brain that receives and processes sensory inputs from the environment via the central nervous system and produces a number of hormones, including the releasing factors. Figure 23.8.
Indole-3-Acetic Acid - The most common auxin hormone found in plants.
Insulin - A 5.8 kD protein synthesized in the B cells of the islets of Langerhans of the pancreas. It is involved in controlling blood glucose levels and stimulates cells to take up glucose form the blood. Figure 23.2
Intracellular Receptors - A class of hormone receptors that exert their effects at the gene level. Table 23.6
Islets of Langerhans - Clusters of pancreatic cells that act as endocrine tissue. There are four different cells types found.
Isoproterenol - An agonist used to treat asthma that acts by interacting with one specific class of adrenergic receptor.
MAPK (Mitogen-activated Protein Kinase) - A class of proteins phosphorylated by MAPKK as part of the central growth factor activation pathway. Figure 23.23
MAPKK - A class of proteins phosphorylated by MAPKKK as part of the central growth factor activation pathway. It phosphorylates MAPK. Figure 23.23
MAPKKK - A class of proteins phosphorylated as a result of ras activation in the central growth factor activation pathway. It phosphorylates MAPKK. The proto-oncogene raf is a member of this family. Figure 23.23
Membrane-Bound Receptors - A class of hormone receptors found in the outer membranes of cells. They may act through three mechanisms, 1. Via a second messenger systems which stimulates production of event inside the cell, 2. As ion channels, which open or close in response to hormone binding, and 3. As a transmembrane protein with a receptor on the outside and a catalytic domain on the inside of the cell that is activated by hormone binding. Figure 23.7
Mitogen - A factor that stimulates mitosis.
Myristic Acid - A fatty acid containing 14 carbons often attached to the -subunit of G proteins.
Oncogene - An altered cellular gene associated with cellular transformation and cancer. Figure 23.19
Oxytocin - A hormone which stimulates uterine contractions in labor.
p53 - A protein of 53 kD in mass that acts in eukaryotic cells as a tumor suppressor. It is involved in regulating the cell cycle.
Pertussis Toxin - A toxin produced by Bordetella pertussis, which binds the subunit of G i protein. It causes whooping cough, lowers blood glucose, and produces hypersensitivity to histamine.
Phosphoinositide System - A cellular system that in response to a hormonal stimuls activate a reaction that stimulates two intracellular messengers, sn-1,2-diacylglycerol (DAG) and inositol 1,4,5 trisphosphate (InsP3). Figure 23.14
Phospholipase C - An enzyme stimulated by the phosphoinositide system. It catalyzes cleavage of phosphatidylinositol 4,5-bisphosphate (PIP2) to create sn-1,2-diacylglycerol (DAG) and inositol 1,4,5 trisphosphate (InsP3). Figure 23.14
Platelet-Derived Growth Factor (PDgf) - A growth factor that interacts with cell surface receptors to stimulate the hydrolysis of phosphatidylinositol.
Prenylation - Attachment of a C 20 isoprenoid moiety onto a molecule.
Preproinsulin - A 105-residue polypeptide that is the precursor of proinsulin and the ultimate source of insulin.
Proinsulin - An 81-residue polypeptide that is an immediate precursor of insulin. It is derived from preproinsulin.
Propranolol - An antagonist of a class of adrenergic receptors which control blood pressure and heartbeat rate.
Proto-oncogene - A cellular gene important in controlling events relating to the growth of the cell. Alteration of the sequence, function, or amount of this gene product may result in transformation of the cell. Such an altered gene is referred to as an oncogene. Figure 23.19
Releasing Factors - Hormones released by the hypothalamus that act to stimulate the anterior pituitary to release specific hormones. Figure 23.8
Retrovirus - A single-stranded RNA virus that goes through a DNA phase as part of its life cycle, due to the presence of reverse transcriptase.
Reverse Transcriptase - A viral enzyme in retroviruses that synthesizes DNA from an RNA template.
Rhodopsin - An abundant membrane protein in the outer segment of rod cells of the retina. Photochemical changes cause this protein to activate transducin to bind GTP.
RU486 - A drug that binds to progesterone receptors and blocks events essential to implantation of a fertilized ovum in the uterus.
Secretin - A substance releasd in the upper small intestine that acts in the stomach to stimulate the flow of gastric juice as an aid to digestion.
Signal Transduction - The process whereby molecules external to a cell can exert their effects inside of a target cell.
Tamoxifen - A drug that binds to estrogen receptors, but does not activate estrogen-responsive genes. It antagonizes estrogen binding in residual tumor cells after surgery.
Transducin - A protein that, upon photochemical stimulation of rhodopsin, is stimulated to bind GTP and activate a phosphodiesterase to cleave cGMP, stimulating a visual cascade of reactions that signal the brain.
Transformation - With respect to cells and cancer, a process whereby cells lose normal growth control mechanisms and in cell culture continue to proliferate under conditions that arrest the growth of normal cells. The cells will produce a tumor if injected into animals.
Transforming Growth Factor - A growth factor that binds to a receptor with a protein serine/threonine kinase activity.
Tropic Hormones (Tropins) - Pituitary hormones that act on other endocrine glands.
Zinc Finger - A protein structural motif involving zinc and cysteine residues found in many proteins that interact with DNA. Figure 23.17