cell signaling

Question 1

Type of signaling

Answer 1

regulatory signals that originate from conditions within the cell.
communication signals that occur between two neighboring cells.
Response to extracellular regulatory signals that are generated to coordinate metabolic activities and other activities essential for the development and survival of organisms.

Question 2

model for initiating a cellular response to an extracellular signal

Answer 2

1. Unoccupied receptor does not interact with G(s) protein.
2. Occupied receptor changes shape and interacts with G(s) protein. G(s) protein releases GDP and binds GTP.
3. Alpha subunit of G(s) protein dissociates and activates adenylyl cyclase
4. When hormone is no longer present, the receptor reverts to resting state. GTP on the alpha subunit is hydrolyzed to GDP, and adenylyl cyclase is deactivated

Question 3

What is an important receptor in pharmacology?

Answer 3

G-protein coupled receptors

Question 4

G-protein coupled receptors

Answer 4

a family of integral membrane cell surface receptors

Question 5

What are G-proteins characterized by?

Answer 5

1. an extracellular ligand-binding domain
2. seven transmembrane spanning domains
3. a cytosolic G-protein activation domain

Question 6

G-protein coupled receptors and ligands

Answer 6

bind to specific ligand. conformational changes due to ligand binding are transmitted to the interior of the cell.

Question 7

Beta and Gamma subunits of the G-protein

Answer 7

act as membrane localizes docking site for the inactive alpha subunit. anchor for alpha

Question 8

alpha subunit

Answer 8

1. binds guanosine nucleotides (GTP/GDP)

1. the inherent ability to hydrolyze GTP to GDP, this is what turns it off.

Question 9

depending on its activation state, the alpha subunit can interact with..

Answer 9

a specific activated GPCR or adenylyl cyclase

Question 10

What determines if a g-protein functions to stimulate (Gs) or inhibit (Gi) adenylyl cyclase?

Answer 10

which family of G protein is linked to a GPCR in a cell type

Question 11

Adenylyl Cyclase

Answer 11

integral membrane enzyme. Enzymatic activity can be stimulated or inhibited by several different proteins, enzymatically utilizes energy from hydrolysis of ATP->AMP + PPi to form cAMP. Generated cAMP quickly

Question 12

cAMP

Answer 12

second messenger produced by adenylyl cyclase.

Question 13

What is the target of cAMP

Answer 13

family of enzymes called protein kinases

Question 14

Protein Kinase A

Answer 14

2 regulatory subunits, 2 catalytic subunits

Catalytic subunits can phosphorylate intracellular effectors.

Question 15

How does cAMP and protein kinase A work together?

Answer 15

cAMP docks with the protein kinase A regulatory cAMP binding sites, and the protein kinase A catalytic subunits are released.

Question 16

What do active protein kinase A catalytic subunits do?

Answer 16

phosphorylate target proteins and enzymes to elicit the function of intracellular effectors driven by extracellular signals

Question 17

intracellular effectors

Answer 17

ion channels, enzymes, DNA binding proteins.

Question 18

Phosphorylation

Answer 18

can positively or negatively affect the activity of an intracellular effector. It does NOT always turn something on.

Question 19

protein phosphatases

Answer 19

enzymes that hydrolytically cleave phosphate esters and thus remove/dephosphorylate effector proteins that are phosphorylated by protein kinases

Question 20

Which amino acids can be phosphorylated

Answer 20

Serine, threonine, tyrosine. they contain an -OH functional group

Question 21

cAMP phosphodiesterase

Answer 21

is an enzyme that rapidly converts cAMP to 5’-AMP (NOT a signaling molecule)

Question 22

Disruption of normal adenylyl cyclase activity

Answer 22

A1 interacts with ADP-ribosylation factors, which catalyzes ADP-ribosylation of G alpha so it can never turn off

Question 23

What is the regulation pathway for intermediary metabolism?

Answer 23

inositol triphosphate and Diacylglycerol signaling

Question 24

phospholipase C

Answer 24

membrane localized, cleaves lipid bilayer PIP2-IP3 and DAG

Question 25

IP3

Answer 25

inositol 1,4,5-triphosphate binds ER receptor, releasing Ca2+ from ER to cytosol

Question 26

PIP2

Answer 26

Phosphatidylinositol 4,5-biphosphate is a membrane phospholipid

Question 27

Protein Kinase C

Answer 27

major target activated by DAG and Ca2+, functions with Ca2+ to synergystically promote (metabolic) responses by phosphorylating proteins, it is cAMP dependent. What promotes change in cellular program

Question 28

What ligand stimulate IP3 and DAG signaling

Answer 28

nurotransmitters, hormones, and growth factors

Question 29

Ca2+ as a signaling molecule in the liver

Answer 29

calcium released from ER, 4 calcium bind to calmodulin, calmodulin-Ca complex results in a conformational change that permits interactions with and activation of enzymes involved in metabolism

Question 30

coordination of energy metabolism is controlled by

Answer 30

Primary-two peptide hormones-insulin and glucagon | Supporting-two catecholamines-epinephrine and norepinephrine

Question 31

insulin

Answer 31

a protein hormone that is water soluble produced in beta cells in the islets of Langerhans in the pancreas stored in secretory granules anabolic effector

Question 32

what does insulin promote

Answer 32

production of glycogen, triacylglycerides, protein

Question 33

regulation of insulin secretion

Answer 33

beta cell secretion of insulin is coordinated with alpha cell secretion of glucagon

Question 34

the rate of glucose use by peripheral tissues as a result of insulin secretion is counter balanced by

Answer 34

glucagon release, hepatic glucose production rates

Question 35

increased insulin secretion from glucose

Answer 35

results in coordinated increase in insulin rate, beta cells produce more insulin, glucagon levels decrease

Question 36

increased insulin secretion from amino acids

Answer 36

increased amino acid concentration and insulin secretion stimulated, glucagon release is unregulated to compensate for the increased insulin and thus glucose uptake

Question 37

increased insulin secretion from GI hormones

Answer 37

peptide hormones are released from the small intestine as anticipatory insulin release stimulators in response to food ingestion, insulin secretion is greater when glucose is ingested in contrast to given IV

Question 38

factors that negatively affect insulin secretion

Answer 38

scarcity of dietary fuels such as glucose and amino acids | Increase in blood levels of epinephrine

Question 39

Epinephrine release is regulated by the nervous system and is secreted by the adrenal medulla in response to

Answer 39

stress, trauma, extreme exercise

Question 40

epinephrine directly affects mobilization of

Answer 40

glucose from the liver | fatty acids from adipose tissue

Question 41

what can override the normal glucose-stimulated release of insulin?

Answer 41

epinephrine