4' phosphopantetheinyl transferase

In molecular biology, the 4'-phosphopantetheinyl transferase superfamily of proteins transfer a 4'-phosphopantetheine (4'-PP) moiety from coenzyme A (CoA) to an invariant serine in an acyl carrier protein (ACP), a small protein responsible for acyl group activation in fatty acid biosynthesis. This post-translational modification renders holo-ACP capable of acyl group activation via thioesterification of the cysteamine thiol of 4'-PP. This superfamily consists of two subtypes: The ACPS type such as E. coli ACPS and the Sfp type such as B. subtilis SFP. The structure of the Sfp type is known, which shows the active site accommodates a magnesium ion. The most highly conserved regions of the protein are involved in binding the magnesium ion.