Acyl-CoA-dependent acyltransferase involved in the synthesis of lupanine alkaloids. Can use both (-)-13alpha-hydroxymultiflorine and (+)-13alpha-hydroxylupanine as substrates. Lower activity with (-)-3beta, 13alpha-dihydroxylupanine, but no activity with (+)-epilupinine and (-)-lupinine as substrates. Tigloyl-CoA, benzoyl-CoA and, more slowly, acetyl-CoA, propionyl-CoA and 2-butenoyl-CoA can act as acyl donors. (2E)-2-methylbut-2-enoyl-CoA + 13-hydroxylupanine = 13-(2-methylcrotonoyloxy)lupanine + CoA Inhibited by N-ethylmaleimide, p-chloromercuribenzoic acid and diethylpyrocarbonate (DEPC). Optimum pH is 8.0. Monomer. Expressed in roots and hypocotyls. Detected in seeds, leaves and cotyledons, but not in young developing leaves. Belongs to the plant acyltransferase family.