Lecture Set 13

Question 1

How can signal molecules act?

Answer 1

Endocrine –> hormones travel long distance by blood stream
paracrine
autocrine
contact dependent/juxtacrine –> signalling molecule attached to membrane of signalling cell

Question 2

How do extracellular signals act?

Answer 2

either slowly (change in gene expression/protein synthesis) or rapidly = anything else

Question 3

How do GPCRs work?

Answer 3

GPCRs are 7pass structures, bind to ligand which then induces change G protein that causes binding to GTP which causes dissociation of G protein into Galpha and Gbeta/gamma subunits

Question 4

How is a GPCR regulated

Answer 4

with a GRK –> phosphorylation deactivates GPCR, at multiply phosphorylation sites and then arrestin attaches

Question 5

What are 4 common intracellular messengers?

Answer 5

1) cAMP from adenylyl cyclase and activates PKA
2) IP3 causes release of Ca2+ from SR
3) DAG activates PKC
4) cGMP activates PKG

Question 6

How are IP3 and DAG formed?

Answer 6

Phosphatidyl inositol (PI) phosphorylated by PI kinase creates PIP (PI 4-phosphate) which is phosphorylated by PIP kinase to PIP2 (PI 4,5-phopsphate) which is phosphorylated by phospholipase C into IP3 and DAG