We used BLAST to compare the rabbit LL sequence with those in the NCBI databases. Comparison of the predicted amino acid sequence of LL with translations of the nucleic acid sequence entries revealed significant similarity to phosphatidylserine phospholipase A
1 (PS-PLA1; expectation value, 4e-45)
21 22 and to a variety of triacylglycerol lipase family members, represented by PLRP2 in an alignment
(Fig. 2A) . The predicted amino acid sequence of rabbit LL (residues 35 to 283) was 42% identical with human PS-PLA1, and 40% identical with human PLRP2. (While this manuscript was under review, two entries representing the human orthologue of rabbit LL were posted in GenBank: accession numbers AY036912 and AK074229. Sequence AY036912 was recently reported to be a membrane-associated phosphatidic acid-selective phospholipase A
1 [mPA-PLA1].
23 )
We generated a phylogenetic tree showing the potential molecular evolutionary relationship of rabbit LL with other members of the triacylglycerol lipase family
(Fig. 2B) . LL is most similar to PS-PLA1 and more distantly related to the other triacylglycerol lipases found on neighboring branches of the tree.
In the human genomic sequence database, BLAST aligned the nucleic acid sequence of rabbit LL with a single, putative human orthologue on chromosome 3 (accession no. Hs3_22705; data not shown). Rabbit LL is approximately 90% identical with the corresponding exons of the human chromosomal sequence.
BLAST also identified several related (85–90% identity) expressed sequence tags (ESTs) in the human EST database. These data imply that the human orthologue of LL may be expressed in normal and tumor tissues of human stomach, colon, pancreas, skin, prostate, and ovary (accession nos. AA102322, AA149791, AA367368, AW845952, AW845987, BF677759, BM752494, BG697821, and T57492).
The rabbit LL sequence predicts a new lipolytic enzyme with an expressed human orthologue.