Definitions:

  • P1 = Specific activity of exogenous [14C]-choline precursor supplied (nCi.nmol-1)
  • P2 = Pool size of exogenous [14C]-choline precursor supplied (nmol.g-1 Fw)
  • A1 = Initial specific activity of cytosolic choline pool (nCi.nmol-1)
  • A2 = Pool size of cytosolic choline pool (nmol.g-1 Fw)
  • A3 = (Vm5*E2)/(Km5+E2) = Rate of synthesis of cytosolic choline from phosphatidyl-choline (nmol.min-1.g-1 Fw)
  • A4 = (Vm6*A2)/(Km6+A2) = Rate of transport of cytosolic choline to the vacuolar choline pool (nmol.min-1.g-1 Fw)
  • A5 = Initial specific activity of vacuolar choline pool (nCi.nmol-1)
  • A6 = Pool size of vacuolar choline pool (nmol.g-1 Fw)
  • A7 = (Vm7*A6)/(Km7+A6) = Rate of transport of vacuolar choline to the cytosolic choline pool (nmol.min-1.g-1 Fw)
  • A8 = (Vm1*P2)/(Km1+P2) = Rate of uptake of exogenous choline (nmol.min-1.g-1 Fw)
  • F1 = Initial specific activity of the pool of chloroplastic choline (nCi.nmol-1)
  • F2 = Initial pool size of chloroplastic choline (nmol.g-1 Fw)
  • F3 = (Vm11*A2)/(Km11+A2) = Rate of transport of cytosolic choline to the chloroplastic choline pool (nmol.min-1.g-1 Fw)
  • B1 = Initial specific activity of the chloroplastic pool of betaine aldehyde (nCi.nmol-1)
  • B2 = Initial pool size of chloroplastic betaine aldehyde (nmol.g-1 Fw)
  • B3 = (Vm8*F2)/(Km8+F2) = Rate of synthesis of betaine aldehyde (nmol.min-1.g-1 Fw)
  • C1 = Initial specific activity of glycine betaine (nCi.nmol-1)
  • C2 = Initial pool size of glycine betaine (nmol.g-1 Fw)
  • C3 = (Vm9*B2)/(Km9+B2) = Rate of synthesis of glycine betaine (nmol.min-1.g-1 Fw)
  • D1 = Initial specific activity of phosphoryl-choline (nCi.nmol-1)
  • D2 = Initial pool size of phosphoryl-choline (nmol.g-1 Fw)
  • D3 = (Vm2*A2)/(Km2+A2) = Rate of synthesis of phosphoryl-choline from choline (nmol.min-1.g-1 Fw)
  • D4 = (Vm4*D2)/(Km4+D2) = Rate of utilization of phosphoryl-choline in choline synthesis (nmol.min-1.g-1 Fw)
  • D5 = Rate of synthesis of phosphoryl-choline from unlabeled phosphoryl-ethanolamine via phosphoryl-monomethylethanolamine and phosphoryl-dimethylethanolamine (nmol.min-1.g-1 Fw)
  • E1 = Initial specific activity of phosphatidyl-choline (nCi.nmol-1)
  • E2 = Initial pool size of phosphatidyl-choline (nmol.g-1 Fw)
  • E3 = (Vm3*D2)/(Km3+D2) = Rate of synthesis of phosphatidyl-choline from phosphoryl-choline (nmol.min-1.g-1 Fw)
  • E4 = (Vm10*E2)/(Km10+E2) = Rate of utilization of phosphatidyl-choline in phosphoryl-choline synthesis (nmol.min-1.g-1 Fw)
  • E5 = Rate of synthesis of phosphatidyl-choline from unlabeled phosphatidyl-monomethylethanolamine via phosphatidyl-dimethylethanolamine (nmol.min-1.g-1 Fw)
  • G1 = Initial specific activity of unlabeled ethanolamine moieties serving as precursors of P-Cho and Ptd-Cho at rates D5 and E5, respectively (nCi.nmol-1)
  • Km1 = Apparent Km of choline uptake system (A8) (nmol.g-1 Fw)
  • Vm1 = Maximal velocity of choline uptake system (A8) (nmol.min-1.g-1 Fw)
  • Km2 = Apparent Km of P-choline synthesis from cytosolic choline (D3) (nmol.g-1 Fw)
  • Vm2 = Maximal velocity of P-choline synthesis from cytosolic choline (D3) (nmol.min-1.g-1 Fw)
  • Km3 = Apparent Km of Ptd-choline synthesis from P-choline (E3) (nmol.g-1 Fw)
  • Vm3 = Maximal velocity of Ptd-choline synthesis from P-choline (E3) (nmol.min-1.g-1 Fw)
  • Km4 = Apparent Km of choline synthesis from P-choline (D4) (nmol.g-1 Fw)
  • Vm4 = Maximal velocity of choline synthesis from P-choline (D4) (nmol.min-1.g-1 Fw)
  • Km5 = Apparent Km of choline synthesis from Ptd-choline (A3) (nmol.g-1 Fw)
  • Vm5 = Maximal velocity of choline synthesis from Ptd-choline (A3) (nmol.min-1.g-1 Fw)
  • Km6 = Apparent Km of choline transport from cytosolic to vacuolar pool (A4) (nmol.g-1 Fw)
  • Vm6 = Maximal velocity of choline transport from cytosolic to vacuolar pool (A4) (nmol.min-1.g-1 Fw)
  • Km7 = Apparent Km of choline transport from vacuolar to cytosolic pool (A7) (nmol.g-1 Fw)
  • Vm7 = Maximal velocity of choline transport from vacuolar to cytosolic pool (A7) (nmol.min-1.g-1 Fw)
  • Km8 = Apparent Km of betaine aldehyde synthesis from chloroplastic choline (B3) (nmol.g-1 Fw)
  • Vm8 = Maximal velocity of betaine aldehyde synthesis from chloroplastic choline (B3) (nmol.min-1.g-1 Fw)
  • Km9 = Apparent Km of glycine betaine synthesis from betaine aldehyde (C3) (nmol.g-1 Fw)
  • Vm9 = Maximal velocity of glycine betaine synthesis from betaine aldehyde (C3) (nmol.min-1.g-1 Fw)
  • Km10 = Apparent Km of P-choline synthesis from Ptd-choline (E4) (nmol.g-1 Fw)
  • Vm10 = Maximal velocity of P-choline synthesis from Ptd-choline (E4) (nmol.min-1.g-1 Fw)
  • Km11 = Apparent Km of choline transport from cytoplasm to chloroplast (F3) (nmol.g-1 Fw)
  • Vm11 = Maximal velocity of choline transport from cytoplasm to chloroplast (F3) (nmol.min-1.g-1 Fw)
  • g Fw = g Fresh weight