Binds medium- and long-chain acyl-CoA esters with very high affinity. Can interact in vitro with arachidonyl-CoA, barely with oleoyl-CoA, but not with palmitoyl-CoA. Confers tolerance and binds to lead ions Pb(2+), probably by promoting lead translocation from roots to shoots. May function as an intracellular carrier of acyl-CoA esters (By similarity). Modulates negatively sterol synthesis during embryogenesis and gametophytes development via interactions with SMO1-1 and SMO1-2; sterols serve as lipid modulators for gene expression of homeodomain-leucine zipper IV transcription factors (PubMed:28500265, PubMed:29288621). Interacts with RAP2-12 (PubMed:22020282). Binds to SMO1-1 and SMO1-2 (PubMed:28500265, PubMed:29288621). Detected in the cell walls of the outer integument cells at the seed coat. Expressed at low levels in roots, stems, leaves, flowers, and siliques, especially within seeds. Strongly expressed in developing ovules (PubMed:28500265). Expressed in embryos at the cotyledons, hypocotyls, procambiums, especially in epidermal cells and axis (PubMed:10363372, PubMed:28500265). Accumulates in imbibed pollen grains and in germinating pollen tubes (PubMed:29288621). Detected in embryo sacs (PubMed:29288621). In roots by lead. Glycosylated. In seeds, localized in the outer integument. Increased sensitivity to lead ions (PubMed:18182029). Proembryo abortion in the double mutant lacking both SMO1-1 and ACBP1 associated with altered fatty acids (FAs) and sterols profiles (PubMed:28500265). Double mutants lacking SMO1-2 and ACBP1 are impaired in seed development, embryo sac development, male and female gamete transmission, and pollen function, as well as altered fatty acids (FAs) and sterols profiles (PubMed:29288621). Belongs to the ACBP family.