Cell signalling pt 2

Question 1

fight or flight response

Answer 1

triggered by a signaling molecule called epinephrine (also known as adrenaline)

Question 2

the cAMP pathway (finish)

Answer 2

-works as second messenger

Question 3

cyclic AMP-inducible Gene Expression

Answer 3

PKA can move to the nucleus where it activates the transcription factor CREB
-rhodopsin

Question 4

rhodopsin

Answer 4

• GPCR found in cells of the eye
• Light (signal) changes the conformation of retinal from cis to trans
• This causes activation of the receptor and exchange from GDP to GTP in the G protein (transducing)

Question 5

Kinases and Phosphates

Answer 5

two classes of kinases/phosphatases:
- serine/threonine kinase
-tyrosine kinase

Question 6

Result of phosphorylation

Answer 6

can change the shape of the proteins (usually activation)
can create a binding site for other proteins (mostly true for tyrosine

Question 7

RTKs

Answer 7

• two functions:
  
  • bind to a signal
  • can function as a kinase
• Ligand bind causes dimerization which brings the kinase domains together

Leads to cross-phosphorylation (the kinase domains will phosphorylate each other)

• Phosphorylation of the receptor creates binding sites for other proteins (proteins that have a SH2 domain)
• A number of RTKs are involved in signaling relating to cell proliferation and survival

Question 8

non- RTKs

Answer 8

• The receptor only binds to the ligand (does not have kinase activity)
• But…the receptor has a protein associate with it that functions as a kinase
• The receptor and the kinase are different proteins
• Allows you to match different proteins together
• Ligand bind causes dimerization which brings the kinases together
• Leads to cross-phosphorylation AND phosphorylation of the receptor

Question 9

JAK/STAT pathway

Answer 9

• This pathway can be activated by cytokines (peptides that allow immune cells to communicate with each other)
• JAK (the kinase) phosphorylate the receptor, thus creating binding sites
• STAT has an SH2 domain and binds to the receptor where it will be phosphorylated
• Phosphorylated STATs dimerize and move to the nucleus to act as a transcription factor
• Cells release cytokines to tell other cells to produce specific proteins

Question 10

integrins

Answer 10

• Integrins are transmembrane proteins that interact with the extracellular matrix
• FAK is a non-receptor tyrosine kinase
• Interaction with the extracellular matrix causes them to cluster leading to cross-phosphorylation

Question 11

MAP kinase pathway

Answer 11

Major pathway activated by enzyme-linked receptors

• Refer to a cascade of protein kinases that is highly conserved in eukaryotes
• They are serine/threonine kinases referred to as MAP kinases

Question 12

PI3-kinase/Akt pathway

Answer 12

• Like the MAP kinase pathway this is usually activated by receptor tyrosine kinases
• This pathway can also be activated via G protein-coupled receptors

Important for cell proliferation and survival

PIP2 is a phospholipid localized in inner mem
PIP3 can bind to a no of diff proteins bringing them in close proximity

Question 13

mTOR pathway

Answer 13

• For a cell to proliferate it needs a proliferation signal (growth factors) AND a good supply of energy
• mTOR pathway links protein synthesis and growth factor availability