Metabolic Biochem 3,4

Question 1

Signal transduction- into to covalent regulation

Answer 1

Signal transduction cascades mediate the sensing and processing of stimuli.
Signal- reception- transduction- translation- response

Question 2

The fasting state

Answer 2

Drop in blood glucose below 4.5mm- triggers glucagon release from the pancreas- normal b glucose is 3.5-5.8
Glucagon causes and increase in blood sugar levels
Activates gluconeogenesis and glycogenolysis in liver
Inhibits glycolysis and glycogenesis

Priority to brain, rbc and retina

Question 3

Glucagon signal transduction pathway in liver- key players

Answer 3

Glucagon (1 messenger)
- secreted in blood when glucose drops <4.5mm
Glucagon receptor
- contains 7 transmembrane helices
Guanyl nucleotide protein
- contains GDP when inactive, GTP when active. Has beta and alpha subunit when loses beta, alpha becomes active.
cAMP (2 messenger)
- link C3 and C5 together.
cAMP dependent protein kinase or protein kinase A
-cAMP activate PKA allosterically activate PKA phosphorylase, several residues on protein targets on Ser/ Thr residues.