phospholipase c cascade

Question 1

what are some examples of the impact of a rise in intracellular Ca2+?

Answer 1

hormone secretion in pancreatic cells, neurotransmitter release in neurones, digestive enzyme release in pancreatic cells, contraction of muscle fibres

Question 2

what are the G protein subunits that activate phospholipase C?

Answer 2

Gao, Gaq

Question 3

What action does PLC take when activated?

Answer 3

hydrolysis of phosphoester bonds converting PIP2 to the second messengers IP3 and DAG

Question 4

what is the function of IP3 and DAG?

Answer 4

IP3 activates IP gated Ca2+ channels, opening them in the endoplasmic reticulum membrane. the calcium released aids PKC in reaching the plasma membrane, where it interacts with DAG and phosphorylates substrates

Question 5

what is the function of PKC?

Answer 5

chromatin regulator in the nucleus, phosphorylating histones, histone modifiers and transcription factors induces growth and differentiation by transcription activation or repression

Question 6

how is the PL pathway terminated?

Answer 6

calcium ions are quickly removed from the cytoplasm by calcium pumps in the plasma membrane and IP3 is quickly hydrolysed to IP2. The intracellular Ca2+ stores are replenished

Question 7

how do hormones trigger the release of other hormones using Ca2+?

Answer 7

a hormone may bind to a pituitary cell and induce a spike in the Ca2+ level that induces release of another hormone

Question 8

what is an example of a hormone that uses the Ca2+ pathway to release another hormone?

Answer 8

luteinizing hormone releasing hormone

Question 9

what are the requirements to form a Ca2+/Calmodulin complex?

Answer 9

4 Ca2+ ions

Question 10

what are some effects of calmodulin activity?

Answer 10

myosin activity, PDE activity, cell growth

Question 11

how can GCPRs have long term effects on cell growth and differentiation?

Answer 11

by affecting gene transcription via phosphorylation of transcription factors (PKA phosphorylates and CBP co activates CREB and it activates transcription of CRE) via the GCPR binding protein arrestin initiating the MAP kinase cascade

Question 12

how is PI converted to the second messengers DAG and IP3

Answer 12

PI is converted to PIP by PI-4 kinase. PIP is converted to PIP2 by PIP-5 kinase. PLC hydrolyses PIP2, forming DAG and IP3