Carrier of the growing fatty acid chain in fatty acid biosynthesis. Lipid metabolism; fatty acid biosynthesis. Seed. 4'-phosphopantetheine is transferred from CoA to a specific serine of apo-ACP by acpS. This modification is essential for activity because fatty acids are bound in thioester linkage to the sulfhydryl of the prosthetic group (By similarity). In rape seeds ACP is coded by two multigene families. There are probably a total of 35 genes. The sequence shown is that of ACL1.C1. Belongs to the acyl carrier protein (ACP) family.