Transfers the 4'-phosphopantetheine moiety from coenzyme A to a Ser of an acyl-carrier-protein. The enzyme is able to transfer the cofactor to a broad range of enzymes with acyl- or peptidyl-carrier protein domains. apo-[ACP] + CoA = adenosine 3',5'-bisphosphate + H(+) + holo-[ACP] kcat is 11 min(-1) with S.mobaraensis apo-PCP BlmI as substrate and 86 min(-1) with S.glaucescens apo-ACP TcmM as substrate. Belongs to the P-Pant transferase superfamily. Gsp/Sfp/HetI/AcpT family.