We have cloned 3 novel murine cDNAs encoding proteins containing an alpha/beta hydrolase fold; a catalytic domain found in a very wide range of enzymes. These proteins belong to the prosite UPF0017 uncharacterized protein family and we have named them lung alpha/beta hydrolase 1, 2, and 3 (LABH) since they were cloned from lung cDNA All have 9 coding exons, encoding 412, 425, and 411 residue proteins respectively (46-48 kDa); LABH1 being closely related to LABH3 having 45% identity. All 3 proteins have a single predicted amino-terminus transmembrane domain. An alignment of family members from different phyla enabled the identification of the LABH1 catalytic triad as Ser211, Asp337, and His366. mRNA expression levels of LABH1 and 3 were highest in liver and LABH2 highest in testis. These findings suggest that the LABH proteins consist of a novel family of membrane bound enzymes whose function has yet to be determined. (C) 2002 Elsevier Science (USA).