Toxicant Effects on Signal Transduction

Question 1

general principles of signal transduction

Answer 1

cell-cell signaling is an essential characteristic of eukaryotic cells it coordinates growth, differentiation, metabolism of cells

Question 2

signaling through extracellular mediator examples:

Answer 2

endocrine
paracrine (what nerves do)
autocrine (self-reinforcement, happens often during development)

Question 3

signaling through cell-cell contact examples:

Answer 3

gap junctions

Question 4

process of signal generation and delivery

Answer 4

ligand -> receptor -> intermediate events -> response

Question 5

intermediate events of extracellular signaling

Answer 5

GTPase switches, second messengers, adapters, protein kinases, transcription factors

Question 6

Signal generation - hydrophilic signals are

Answer 6

synthesized and stored in secretory vesicles

secretion is often regulated by calcium

Question 7

Signal generation - hydrophobic signals are

Answer 7

typically released as soon as they are generated

the half-life of a hydrophobic signal determines a chronic, endocrine response or a transient paracrine response

Question 8

exocytotic release; what hypothesis is used?

Answer 8

the SNARE hypothesis

Question 9

SNARE’s are

Answer 9

integral membrane proteins that are found on both the vesicles and the target membranes

Question 10

v & t SNARES form a high-affinity complex that contributes to

Answer 10

vesicle docking fusion

Question 11

the docking process is regulated by the

Answer 11

small GTPase Rab3A

Question 12

the fusion process is regulated by

Answer 12

calcium binding proteins like synaptotagmin

Question 13

increase in intracellular calcium triggers what??

Answer 13

fusion of vesicles with the plasma membrane which results in releasing of neurotransmitter into synpatic cleft

Question 14

how does a cell convert stimuli into response?

Answer 14

acute and chronic signaling

Question 15

acute response

Answer 15

modification of already existing enzymes in the target cells

primary effect of ligands that bind to cell surface receptors

Question 16

chronic response

Answer 16

alteration of pattern of gene expression
primary effect of ligands that bind to intracellular receptors
common later effect of ligands that bind to cell surface receptors

Question 17

3 major classes of cell surface receptors

Answer 17

1. ion channel coupled
2. GPCR
3. enzyme coupled

Question 18

voltage-gated ion channels

Answer 18

are on the plasma membrane of all electrically excitable cells

Question 19

GPCR’s

Answer 19

-have 7 transmembrane spanning alpha-helicies with their N terminus extracellular and their C terminus intracellular

Question 20

GPCR binding

Answer 20

ligand -> receptor -> G protein -> effector

Question 21

what is the effector with GPCRs?

Answer 21

its an ion channel or an enzyme that generates a second messenger

Question 22

Examples of GPCR

Answer 22

morphine, ergot, atropine, cocaine

Question 23

covalent modification can

Answer 23

direct location, activity or interactions of proteins with others

Question 24

acute effects mediated by kinases

Answer 24

activation/inhibition of enzymes

Question 25

chronic effects of kinases

Answer 25

activation/inhibiton of transcription factors