Members of this family transfers the 4'-phosphopantetheine (4'-PP) moiety from coenzyme A (CoA) to the invariant serine of Pfam:PF00550. This post-translational modification renders holo-ACP capable of acyl group activation via thioesterification of the cysteamine thiol of 4'-PP [1]. This superfamily consists of two subtypes: The ACPS type such as Swiss:P24224 and the Sfp type such as Swiss:P39135. The structure of the Sfp type is known [3], which shows the active site accommodates a magnesium ion. The most highly conserved regions of the alignment are involved in binding the magnesium ion.

1: Cloning, overproduction, and characterization of the Escherichia coli holo-acyl carrier protein synthase. Lambalot RH, Walsh CT; J Biol Chem 1995;270:24658-24661. PMID:7559576

2: A new enzyme superfamily - the phosphopantetheinyl transferases. Lambalot RH, Gehring AM, Flugel RS, Zuber P, LaCelle M, Marahiel MA, Reid R, Khosla C, Walsh CT; Chem Biol 1996;3:923-936. PMID:8939709

3: Crystal structure of the surfactin synthetase-activating enzyme sfp: a prototype of the 4'-phosphopantetheinyl transferase superfamily [In Process Citation] Reuter K, Mofid MR, Marahiel MA, Ficner R; EMBO J 1999;18:6823-6831. PMID:10581256