Inositol-phospholipid signaling pathway Flashcards Preview

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Flashcards in Inositol-phospholipid signaling pathway Deck (4)
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1

Inositol-phospholipid signaling pathway

-Receptor R1 vings to a ligand which activates a G-protein-> Gq
-Gq then activates PLC
-PLC hydrolyzes PIP2 producing DAG and IPG
-IPG diffuses to the ER where it binds to Ca2+ channel which cause the channels to open and Ca2+ enters the cell
-Ca2+ activates Ca2+-dependent protein kinases

-PKC then binds to DAG which activates them
-PKCs phosphorylate target proteins-changing their activities

2

Adenylyl Cyclase Signaling Pathway

-Stimulatory Hormone binds to the stimulatory receptor, which activates it
-Stimulatory receptor then activates a G-protein (Gas)-GTP
-Gas-GTP activates Adenylyl cyclase which synthesizes cAMP
-cAMP then binds to PKA which releases C subunit from R subunit and activates the PKA
-PKA then phosphorylates target proteins at Ser, Thr which activates them

3

Adenylyl Cyclase Signaling Pathway Inhibtion

-An inhibiting hormone binds to a receptor (Ri) which activates Gia by stimulating exchange of GTP in place of GDP
-Gia-GTP inhibits adenylyl cyclase and subsequent steps are reversed

4

Receptor Tyr Kinase Signaling

(insulin Receptor)
-work with growth factors and insulin
1) tyrosine kinase domains of the receptor in the inactive state are separated, but once the ligand binds a conformational change brings them together and there is a autophosphorylation

-in the insulin pathway: the insulin receptor phosphorylates IRSs-these activate a number of kinases involved in nutrient utilization
-one of the IRSs activates PIP2
-PI phosphorylates PIP2 to PIP3
-PIP3 activates PIP3-dependent protein kinases