mod 6

Question 1

types of signalling

Answer 1

endocrine (sinalling molecules are hormones)
paracrine: signalling are local mediators (growth factors, NO) produced at low []
autocrine: local mediators, low [], need receptors
neuronal: neurotransmitters
contact-dependent: cell surface and receptor contact
direct: flow of molecular traffic, gap junctions or plasmodesmata

Question 2

the four types of cell surface receptors

Answer 2

1. ion-channel- coupled receptors
2. G-protein-coupled receptors
3. enzyme-coupled receptors
4. nuclear receptor

Question 3

2 major signal mediators

Answer 3

signalling by phosphorylation (GEF)
&
signalling by GTP-binding (GAP)

Question 4

what is Kd

Answer 4

the dissociation constant (describes the affinity)

Question 5

G-protein coupled receptors (GPCRs)

Answer 5

there are 7 transmembrane spanning regions, and more than 800 GPCRs in the human genome, 40-50% of drugs target the GPCR activity

Question 6

what did reed and Jones discover?

Answer 6

the G protein was identified in 1989

Question 7

what are the 2 types of G proteins

Answer 7

monomaric and heterotrimeric g-protein

Question 8

flight or fight

Answer 8

is kinases mediated, cAMP is the secondary messenger which activates a protein kinase called PKA (protein kinase A), results in increased glucose for muscle cells, glucagon or beta adrenergic is the receptor

Question 9

PKA activation

Answer 9

increased cAMP levels lead to the PKA activity, when binded the subunits fall off allowing catalysis. the PKA can reguate gene expression

Question 10

inositoltrisphosphate and diacylglycerol

Answer 10

both secondary messengers, initiated by phospholipase C

Question 11

Calmodulin

Answer 11

involved in Ca signalling, it binds and activated other proteins, can change structure upon calcium binding and can reguate protein targets

Question 12

Cytosolic domain has what features?

Answer 12

either has protein kinase activity or associates w a protein kinase, are bound often by growth factors

Question 13

what are the 2 classes of protein kinase receptors

Answer 13

tyrosine kinase receptors and serine/threonin receptor kinases

Question 14

what is the structure of teh tyrosine kinasses

Answer 14

unbounded, transautophosphorylation activates the receptor

Question 15

Ras

Answer 15

monomeric GTPase, the SOS is activated by indirect binding ovia GRB2 to the receptor kinase

Question 16

MAP kinase pathway

Answer 16

mitogen activated protein, RAS output starts the MAPV

Question 17

Insulin pathway

Answer 17

insulin receptor binds to insulin and can activate the ras pathway, this leads the conversing of PIP3 which binds to a protein kinase called Akt. Akt catalysis phorphorylation leading to increase of glycogen synthase activity

Question 18

steroid hormone signalling

Answer 18

receptors are in the cell as the signal can pass thru the membrane easily. bound receptors travel to the nucleus

Question 19

histidine kinase associated receptors

Answer 19

used by bacteria and yeast and plants, mediated bacterial chemotaxis. use Ca for signalling