Probable bifunctional protein. The phosphorylated protein plays an important role in the elongation step of protein synthesis (By similarity). The phosphopantetheinylated protein acts as an acyl carrier protein. The phosphorylated form is part of the ribosomal stalk involved in the interaction of the elongation factors with the ribosome during protein synthesis (By similarity). The phosphopantetheinylated form is part of the 10S triacylglycerol biosynthetic complex involved in de novo fatty acid biosynthesis. 4'-phosphopantetheine is transferred from CoA to a specific serine by acpS. This modification is essential for activity because fatty acids are bound in thioester linkage to the sulfhydryl of the prosthetic group. Belongs to the eukaryotic ribosomal protein P1/P2 family.