Signal Transduction

Question 1

Importance of protein interaction domains

Answer 1

selectively recognize specific structural motifs and bind them with high affinity and specificity

Question 2

Covalent modifications

Answer 2

revisable ones change function of certain proteins and lipids

Question 3

Receptor proteins

Answer 3

way for transmembrane communication of hormonal signals

cluster of these receptors are called signalsomes

Question 4

Hormone

Answer 4

primary messenger

Question 5

Receptor

Answer 5

binds the primary signal

Question 6

Transducer

Answer 6

relays the signal, amplifies the response

Question 7

Physiological response

Answer 7

cell division (or other responses)

Question 8

Types of signaling hormones

Answer 8

steroid, amino acid derivatives, peptide

Question 9

Steroid hormones

Answer 9

derived from cholesterol, regulate metabolism, salt and water balance, inflammatory responses, and sexual function

Question 10

Amino acid derivatives

Answer 10

example: epinephrine

regulates smooth muscle function, blood pressure, cardiac rate, and the thyroid hormones

Question 11

Peptide hormones

Answer 11

regulate the processes in all tissues, including release of yet other hormones

Question 12

Nonsteroidal hormones action on cell

Answer 12

exclusively at the plasma membrane

Question 13

Steroid hormones action on cell

Answer 13

either at the nucleus or at intracellular or extracellular plasma membrane receptors

Question 14

Single-transmembrane-segment catalytic receptors

Answer 14

intracellular domain that is either a tyrosine kinase or a guanylyl cyclase (ligands larger peptide hormones)

Question 15

G-protein-coupled receptors

Answer 15

integral membrane proteins with an intracellular site for a GTP-binding protein (small molecule ligands)

Question 16

Oligomeric ion channels

Answer 16

multisubunit structures that function as ligand-gated ion channels (ligands for these channels are neurotransmitters)

Question 17

Transduction of receptor signals

Answer 17

1) exchange of GDP for GTP by GTP-binding proteins –> generation of 2nd messengers
2) receptor-mediated activation of phosphorylation cascades
3) conformation changes that open ion channels or recruit proteins into nuclear transcription complexes

Question 18

Heterotrimeric G proteins

Answer 18

have alpha, beta, and gamma units

alpha subunits binds GDP or GTP and has an intrinsic GTPase activity

Question 19

Cholera toxin

Answer 19

effects Gs, ADP ribosylation of an Arg residue in the alpha-s subunit of Gs causes an inhibition of associated GTPase activity

Question 20

Pertussis toxin

Answer 20

effects Gi, ADP ribosylation of a Cys residue in the alpha-i subunit of Gi causes an inability to inhibit adenylate cyclase activity

Question 21

MAP-kinase Ser/Thr phosphorylation pathway

Answer 21

Ras activates MAP-KKK –> activates MAP-KK –> activates MAP-K –> phosphorylates a variety of downstream proteins

Question 22

Phospholipase mediated signaling

Answer 22

some second messengers are generated by breakdown of membrane phospholipids

Question 23

G proteins stimulate

Answer 23

PLC-beta

Question 24

Receptor tyrosine kinase stimulate

Answer 24

PLC-gamma

Question 25

Ca-dependent molecules

Answer 25

all PLC

Question 26

Calcium ion role in cell

Answer 26

intracellular signal, binding of certain hormones causes rapid increase in cytoplamsic Ca levels

Question 27

Calcium ion regulate processes

Answer 27

protein kinase C, calcium-modulared proteins, annexin proteins

Question 28

Integrations of signaling pathways

Answer 28

activation of a ribosomal serene.threonine kinase known as rsk1 requires phosphorylation by 2 protein kinases, they come through different signaling pathways