This is a family of alpha/beta hydrolases which may function as lipases. This domain is the catalytic domain and includes the catalytic triad and the GXSXG sequence motif which is a characteristic of these enzymes [1].

1: Novel transmembrane lipases of alpha/beta hydrolase fold. Lazniewski M, Steczkiewicz K, Knizewski L, Wawer I, Ginalski K; FEBS Lett. 2011;585:870-874. PMID:21333648