FIG. 4.

Effects of acyl-ACPs on ACC partial reactions. Biotin carboxylase (A) was assayed by carboxylation of biotin with [¹⁴C]bicarbonate, whereas carboxyltransferase (B) was assayed in the reverse of the physiological reaction by decarboxylation of [2-¹⁴C]malonyl-CoA in the presence of d-biotin-ɛ-lysine (8). The extracts were incubated with palmitoyl-ACP as described in the legend to Fig. 2. Symbols: ▵, partial activities of an extract that contained all four overproduced ACC subunits; ▿, biotin carboxylase activity of an extract that contained overproduced AccC subunit; ○, carboxyltransferase activity of an extract that contained all overproduced AccA and AccD subunits (8). The 100% activity for biotin carboxylase was 4.6 nmol/min/mg of protein, whereas that for carboxyltransferase was 28.4 nmol/min/mg of protein.