Human metabolism lecture 5

Question 1

General

Answer 1

• Fuel = blood glucose, muscle glycogen, blood FA, muscle TAGs

Question 2

Controlling metabolism by E status

Answer 2

• AMP/ATP sensed + by AMPL
• adenylate kinase amplifies small ↓ in [ATP] to ↑ in [AMP]
• glycogen phosphorylase b = stimulated by ↑ AMP/ATP
• PFK = regulated by ATP
• Bypass hexokinase so 3ATPs made per glucose

Question 3

AMPK

Answer 3

• GS + HMG Coa reductase are both phosph + inhibited by AMPK
• ACC2 is phosph + inhibited
• When AMP/ATP ↑, kinase active, ACC-P inhibited, x malonyl coA made, CPT-1 de-inhib, rate of FA ox ↑

Question 4

Controlling metabolism by nervous control

Answer 4

• Mediated by Ca2+
• Glycogen phosphorylase b (gamma subunit binds Ca2+, activates y subunit of phosphorylase b kinase which phosph + activates glycogen phosphorylase)
• PDH (PDH phosphatase = stimulated by Ca2+, dephosph PDH → active form)
• Isocitrate / a-ketoglut dehydrogenase

Question 5

Adrenaline

Answer 5

1. glycogen breakdown in muscle + liver
   - adrenaline → cAMP → activates PKA → PKA phosph phosphorylase b kinase which phosph glycogen phosphorylase → ↑ G6P + ATP
   - PKA phosph + inhibits PP1
2. TAG lipolysis in adipose
   - HSL phosph by PKA, ↑ activity
   - Perilipin 1 phosp by PKA → fragmentation of perilipin 1 barrier