Cell Signaling

Question 1

types of detectors of extracellular signaling

Answer 1

voltage-dependent Ion Channels, Ligand dependent Ion channels, G-protein coupled Receptor, Enzyme Linked Receptor, Nuclear Receptors

Question 2

“tools” of the signaling pathway

Answer 2

1)Receptors, 2)Second messangers: Ca2+ (extracellular or intracellular), cAMP (by AC or Adenylate cyclase), IP3 (inositol triphosphate in cytosol from PLC or Phospholipase C), DAG (diacylglycerol in membrane), NO (nitric oxide, cell permeable from NOS or Nitric oxide synthase), 3)Other steps like protein mod, protein protein binding, and GTP/GDP exchange

Question 3

pathway for amplification

Answer 3

signaling cascade. 1 -> 2 -> 4, positive feedback loops (Ca++ loops)

Question 4

signal termination (3)

Answer 4

Constitutively active terminators (ie pumps, PDE, intrinsic GTPase, Phosphatase), signal induced terminators (phosphatase, GAP enhanced GTPase), Negative Feedback mechanisms

Question 5

pathway for termination

Answer 5

Extracellular signaling molecules, Receptor desensitization or internalization, 2nd messager pumps. Metabolic mod (cAMP to AMP via PDE), de/phosphorylation, protein degredation, and GTP binding proteins

Question 6

Phosphodiesterase

Answer 6

PDE5: 2 binding sites for cGMP, one non-catayltic that enhances binding of next cGMP (vice versa), and catalytic site that turns cGMP to GMP. PDE5 is also phosphorylated by PKG, which enhances binding (and vice versa, binding increases phosphorylation). target of viagra, example of co-operative stimulation

Question 7

crosstalk

Answer 7

crossing and stimulation (or blocking or modulation) of one pathway by another pathway in the pathway network

Question 8

nodes

Answer 8

point in a network that has multiple inputs and/or outputs (like Ca++)

Question 9

modules

Answer 9

process signals together (don?t need to consider individual components but you are looking at a subsection to understand something)