Cell signaling part III

Question 1

what are the 2 kinds of ion channel receptors

Answer 1

ligand gated channels and neuronal and excitable cells

Question 2

excitatory synapses are usually

Answer 2

cation channels, who open due to depolarization

Question 3

inhibitory synapses are usually

Answer 3

anion channels, whose opening cause is hyperpolarization

Question 4

the selectivity of channel depends on

Answer 4

charged AA residues on the central pore

Question 5

what are the 2 kinds of nicotinic ACh receptors

Answer 5

~muscular receptors - present at neuromuscular junctions
~neuronal receptors - can be homomeric (only one alpha unit) or heteromeric (combination of alpha and beta) they are expressed in autonomic ganglia, CNS, adrenal medulla

Question 6

enzyme linked receptors have 3 intinsi activities

Answer 6

~RTK
~Receptor serine/threonine kinases
~receptor guanylyl cyclases

Question 7

associated enzymatic activity is done by

Answer 7

tyrosine kinases associated receptors

Question 8

RTK are

Answer 8

have an intracellular catalytic domain (tyrosine kinase), have a single transmembrane domain, have an extracellular ligand binding domain

Question 9

many growth factors act on

Answer 9

RTK

Question 10

growth factors and RTK influence

Answer 10

cell growth, proliferation, differentiation and development, tissue homeostasis and repair, survival and death, migration

Question 11

how are RTK activated by ligands

Answer 11

their binding activates RTK by inducing dimerization and auto phosphorylation.
EXCEPT: the insulin growth factor

Question 12

Ras protein

Answer 12

is a membrane bound monomeric G protein and is activated by RTK

Question 13

what happens when Ras is activated

Answer 13

~it activates a series of MAPK
~each kinase upstream in the pathway phosphorylate another kinase and activates it
~eventually the signal reaches the nucleus

Question 14

what is the link between RTK and PI3 kinase

Answer 14

RTK might activate PI3 once bound to it, this acts as a docking site for signaling proteins, it is mediated by kinase Akt- blocks intracellular death factors

Question 15

activated RTK influence PLC in 2 ways

Answer 15

by localizing the enzyme to the membrane , or by phosphorylating it

Question 16

main effects of NO

Answer 16

~ vasodilation
~ anti-inflammatory
~ anti-thrombotic

Question 17

how does NO function

Answer 17

in target cells NO binds to the guanylyl cyclase, initiating cGMP production, the cell relaxed (vasodilates) thus nitroglycerin is used against angina pectoralis