The PC-Esterase family [1] is comprised of Cas1p, the Homo sapiens C7orf58, Arabidopsis thaliana PMR5 and a group of plant freezing resistance/cold acclimatization proteins typified by Arabidopsis thaliana ESKIMO1 [2][3], animal FAM55D proteins, and animal FAM113 proteins. The PC-Esterase family has features that are both similar and different from the canonical GDSL/SGNH superfamily [1]. The members of this family are predicted to have Acyl esterase activity and predicted to modify cell-surface biopolymers such as glycans and glycoproteins [1][3]. The Cas1p protein has a Cas1_AcylT domain, in addition, with the opposing acyltransferase activity [1]. The C7orf58 family has a ATP-Grasp domain fused to the PC-Esterase and is the first identified secreted tubulin-tyrosine ligase like enzyme in eukaryotes [1]. The plant family with PMR5, ESK1, TBL3 etc have a N-terminal C rich potential sugar binding domain followed by PC-Esterase domain [1].

1: Novel eukaryotic enzymes modifying cell-surface biopolymers. Anantharaman V, Aravind L; Biol Direct. 2010;5:1. PMID:20056006

2: Involvement of TBL/DUF231 proteins into cell wall biology. Bischoff V, Selbig J, Scheible WR; Plant Signal Behav. 2010; [Epub ahead of print] PMID:20657172

3: ESKIMO1 disruption in Arabidopsis alters vascular tissue and impairs water transport. Lefebvre V, Fortabat MN, Ducamp A, North HM, Maia-Grondard A, Trouverie J, Boursiac Y, Mouille G, Durand-Tardif M; PLoS One. 2011;6:e16645. PMID:21408051