Week 5 Transport - Drewes

Question 1

NO- chemical messenger

Answer 1

Ach leaves the nerve
activates NOS which converts arginine to NO
NO leaves the cell, diffuses into another and Guanylyl cyclase which converts GTP to cGMP
cGMP causes relaxation and vasodialation
cGMP phosphodiesterase cleaves cGMP deactivating it (viagra inhibits phosphdiesterase inhibiting the breakdown of cGMP)

Question 2

Ach in nerve (ligand gated example) also (ion gated channel example)

Answer 2

depolarization opens Ca channels
Ca channels cause release of Ach
Ach binds to Ach receptors which open Na+ channels –> depolarization of the membrane which open voltage gated Na+ channels

Question 3

G protein receptors

Answer 3

7 transmembrane domains
ligan binds receptor
beta gamma dissociate
GDP on alpha subunit gets “phosphoylates” to GTP–> active
Finds adneylyl cyclase and binds/ activates which converts ATP cAMP and GTP back to GDP (inactiving the alpha subunit)

Question 4

Cholera (AB toxin)- g protein coupled receptor example

Answer 4

activates GPCR to generate cAMP opens CFTR channel
Chloride leaves
Cholera inhibits hydrolysis of GTP to GDP on alpha subunit, keeps activating adenylcyclase (no way to shut signal off)

Question 5

phosphotidyl inosital- GPCR

Answer 5

ligand bind receptor
alpha subunit activated
alpha subunit activates phosphlipase C
phospholipase C cleaves PIP 2 into DAG and IP3
IP3 goes to ER and binds IP3 gated ion channel, and releases Ca+
Ca+ can activate PKC

Question 6

Ryanodine Receptor (second messanger anestitic)

Answer 6

on sarcoplasmic reticulum in muscle cells. uncontrolled release of Ca

Question 7

Tyrosine Receptors- Ras

Answer 7

Growth factor binds
tyrosine homodimer phosphorylates eachother
Activates “adaptor protein” which activates RAP
RAS+GDP –> RAS+GTP which MAP kinase (KKK), enters nucleus and promotes growth

Question 8

JAK-STAT receptors (examples kinase receptor)

Answer 8

ligand bind receptor
JAK proteins phosphorylate the tyrosine receptors and themselves
STAT binds phosphorylated tyrosines
JAKS phosphorylate STATs
(P) STATS dissociate and dimerize go to nucleus and acts as a TF

Question 9

Serine-Threonine Receptors

Answer 9

ligand bind receptor
Serine or Threonine auto phosphorylate
Which (P) RsMAD
RsMAD combines with coSMAD and enters nucleus