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| Also known as alpha cells are found in the islets of langerhans in the pancreas. The A-cells produce glucagon and peptides derived from glucagon precursors. |
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| On the nicotinic acetylcholine receptor, there are 2 alpha subunits which are identical and bind to acetylcholine; the insulin receptor also has 2 identical alpha subunits. |
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| Neurotransmitter that acts on nicotinic acetylcholine receptors on the plasma membrance of certain muscle cells |
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| Enzyme that terminates the effect of acetylcholine: located on the post synaptic membrane |
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| An electrical stimulus which signals neurons to release/secrete neurotransmitters. It is a voltage difference across the plasma membrane caused by changes in Na+ and K+ gradients, propagated along a nerve. (ACh-esterase prevents the action potential from occurring) |
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| The cholera A toxin, an NAD- glycohydrolase, cleaves NAD and transfers the ADP ribose portion to other proteins. This action contributes to the inhibition of the GTPase activity in heptahelical receptors. |
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Definition
| The ADP ribose from above is transferred to the Gas subunit of heterotrimeric G- proteins, which inhibits the ability of the GTP to hydrolyze itself in the heptahelical receptor. |
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| When activated, after a hormone binds, it synthesizes cAMP from adenosine triphosphate (ATP) --levels change rapidly in cells as hormone levels change. Part of signal transduction in heptahelical receptors with heterotrimeric g-proteins. |
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| Releases cortisol in response to stress; located on the kidneys-diffuses cortisol into the bloodstream. |
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| Stimulates beta 2 receptors, promotes insulin release - part of the adrenal gland, located in its center, surrounded by adrenal cortex - secretes hormones, "fight or flight" - adrenaline, noradreneline, dopamine (catecholamines --> epinephrine and norepinephrine) |
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Definition
| When a hormone like insulin or glucagon bind to their respective receptors, the tyrosine kinase domains of the receptor dimers phosphorylate each other on certain tyrosine residues. |
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| Chemical messenger - acts on the cell from which it is secreted or on nearby cells of the same type. |
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| A disorder where production of antibodies are directed against one's own immune system - cells attacking "self" cells which are seen as biologic invaders. |
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Definition
| Work through the Gas and stimulate adenylyl cyclase. It is a type of hetahelical receptor, which epinephrine binds to. Also found in the insulin receptor. (Same as beta subunit). Part of a G-protein also. |
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Definition
| Small non-protein compound acts as second messenger - generated from inside the cell in response to messenger binding to the receptor. Continues intracellular message transmission. |
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Definition
| Enzyme that resides in plasma membrane - hydrolyzes cAMP to AMP. |
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| Calcium ion channels that open in the plasma membrane of cells when action potential reaches them - channels open, cells flood with Ca2+. Triggers release of acetylcholine into the synaptic cleft. Binds to troponin-C and allows muscle contraction. |
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Definition
| A calcium binding protein. Upon binding to calcium it undergoes a conformational change, this change allows it to be able to bind to specific proteins to elicit a certain response. |
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| Due to the cholera A toxin, the cAMP cascade activates this channel, resulting in a secretion of chloride ion and sodium ion into the intestinal lumen, which is followed by water, causing diarrhea and vomiting. |
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Definition
| An anion that is involved in a membrane pump. |
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| A steroid hormone released from adrenal cortex--diffuses into blood stream--acts on tissues to change enzyme levels and redistribute nutrients in preparation for acute stress (such as low blood sugar). |
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| Product (with IP3) of reaction catalyzed by phospholipase C (PLC) - functions as a second messenger signaling lipids - remains within plasma membrane-facilitates translocation of PKC from cytosol to plasma membrane |
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Definition
| Chemical messengers that transmit messages between cells; travel in the blood (i.e., hormones). |
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| A membraneous network within the cytoplasm of cells involved in the synthesis, modification, and transport of cellular materials. |
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| Catecholamine hormone - fight, flight,fright hormone - released from adrenal medulla in response to stress - travels in blood through body- FAST ACTING; diffuse. |
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Definition
| A vesicle joins the presynaptic membrane as it dumps its contents into the synaptic cleft (gap). |
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Definition
| Activated by Alpha adrenergic receptors - then, activates phospholipase C - creates DAG and IP3 as second messengers. |
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Definition
| Stimulates adenylyl cyclase to produce cAMP, a 2nd messenger. It is a subunit of Heterotrimeric G-protein. |
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Definition
| Guanosine diphosphate - it is the product of GTP (guanosine triphosphate) dephosphorylation by GTPases. it is converted to GTP additionally with the help of pyruvate kinase and phosphoenolpyruvate. Found in signal transduction that uses tyrosine kinase receptors and heptahelical receptors. |
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Definition
| Guanosine triphosphate - Activated by SOS in signal transduction by tyrosine kinase receptors, and exchanged in the plasma membrane for GDP (guanosine diphosphate). Causes a conformational change that binds protein Raf. Also found in signal transduction through heptahelical receptors - causes dissociation of the a-subunit from the receptor and the beta and gamma-subunits. |
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Definition
| In the plasma membrane, controls exchange of ions; action potential generates secretion of neurotransmitter, which opens ion channels. Ions diffuse into/out of the cell through the channel. Electrical changes in the membrane regulate the opening and closing of the channel, in response to voltage differentials. |
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Definition
| An endocrine hormone, secreted in response to low blood glucose levels- acs on the liver to stimulate release of glucose from glycogen stores. |
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Definition
| In the fasting state- formation of new glucose - converts non-carbohydrate precursors to glucose-lactate, glycerol, and amino acids used as carbon sources to synthesize glucose. |
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Definition
| The lysis, or splitting of glycogen, to form glucose subunits. |
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Definition
| Adaptor protein, has an SH2 domain, binds to phosphotyrosine residues on growth-factor receptors, causes conformationa change-activates SH3 domain. |
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Term
| heterotrimeric G protein: |
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Definition
| A G- protein consisting of three subunits (alpha, beta, and gamma). Part of signal transduction using a heptahelical receptor. When a hormone binds, a GDP bound to the alpha subunit dissociates and a GTP associates, and the alpha subunit dissociates from the beta and gamma subunits. |
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Definition
| Helpful in the transportation of fats all through the body, as well as helps in the communicating of neurons with the body's nervous system. |
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Term
| 1,4,5-trisphosphate (IP3): |
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Definition
| produced through hydrolysis of phospholipid PIP2, diffuses into cytosol, stimulates release of Ca2+ ions from the smooth ER. Produced when PI-4,5-bisP is cleaved by phospholipase C (PLC). |
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Definition
| Hormone that regulates glucose metabolism and energy in the body. Causes cells in the liver, muscle, and fat to take up glucose from blood, storing it as glycogen in the liver and muscles; stops the use of fat as an energy source. Produced by the beta cells of the pancreas. |
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Definition
| Member of Tyrosine Kinase family of receptors. Exist in membrane as pre-formed dimer; each 1/2 contains identical Alpha and Beta subunits. Activated receptor is phosphorylated and binds IRS (insuling receptor substrate) which is also phosphorylated; creates multiple binding sites for proteins. |
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Definition
| Any substance that is acted upon by an enzyme. |
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Definition
| This internal clock has to do with the fact that the GTP bound to the alpha subunit of the heterotrimeric G protein hydrolyzes itself when it needs to be inactivated. |
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Definition
| A protein or receptor that is embedded within the membrane, therefore polar molecules cannot bind to these receptors, only non-polar signaling molecules may bind to these. |
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Definition
| Sodium; key molecule for the maintainence and functioning of the intracelllular membrane. In cells, sodium diffuses into a cell in response to an action potential which opens gated ion channels. K+ (potassium) diffuses out. This causes the change in membrane potential. |
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Definition
| Nicotinamide Adenine dinucleotide, a coenzyme. |
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Definition
| Hormone similar to epinephrine - released from adrenal medulla in response to short-term stress; fight or flight group of hormones; fast acting, diffuse throughout body. In contrast to epinephrine, norepinephrine contributes more to stabilizing the normal activities of the body after stress rather than preparing the body for an emergency. |
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Definition
| Endocrine gland, produces insulin, glucagon. Also acts as exocrine gland, secretes digestive enzymes. |
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Definition
| Chemical messengers that transmit messages between cells; travel between nearby cells. |
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Term
| phosphatidylinositol 3,4,5 trisphosphate (PI-3,4,5-trisP): |
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Definition
| Serves as plasma-membrane docking site for signal transduction proteins that contain pleckstrin homology (PH) domains. |
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Term
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Definition
| Class of enzymes that cleave phospholipids right before the phosphate group. |
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Definition
| Phosphorylates PI 4,5-bis-phosphate to PI 3,4,5-tris-phosphate. It is involved in cell growth, proliferation, differentiation, motility, survival, and intracellular trafficking. |
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Term
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Definition
| Specific sequence of amino acids on an intracellular protein - binds protein to plasma membrane. Attaches to docking sites provided by P1-3,4,5-trisP. |
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Definition
| where AChE resides; cleaves Acetyl choline by hydrolysis; terminates action potentials |
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Definition
| Enzymes that are dependent on the activity of cAMP in a cell. it is also known as cAMP-dependent protein kinase. Its main function is in regulation including the regulation of glycogen, glucose and lipid metabolism. |
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Definition
| Class of enzymes which are responsible for controlling the function of other proteins through phosphorylation of hydroxyl groups of serine and threonine amino acid residues on these proteins. |
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Definition
| "SRC" homology 2 domain - protein having this domain binds to a phosphotyrosine residue on the receptor - very specific, binds to specific phosphorylated tyrosine residues. |
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Term
| signal transduction pathway: |
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Definition
| Sequence of events after the chemical messenger binds to a receptor that ends in a cellular response. |
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Term
| signal transducer proteins: |
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Definition
| Any proteins, within the cells that are bound to a membrane-bound hormone receptor. Changes conformation in response to a chemical messenger binding to a receptor outside the cell. |
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Definition
| A subdivision of a protein (ie., receptor). |
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Definition
| The space or junction that allows a neuron to pass an electrical or chemical signal to another cell. |
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Definition
| Attached to the intracellular side of the plasma membrane by covalently bonded lipid anchors. |
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Definition
| Synthesis of mRNA - transcription regulates the "make up" of DNA at specific sites. Can be gene specific or site specific. |
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Definition
| Tyrosine kinase receptor sites in the cell that are bound by growth factor and dimerized; the domain then phosphorolyates each other forming specific binding sites for signal transducer proteins |
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Definition
| Hold acetylcholine; clustered near the pre-synaptic membrane. |
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