Approximately 2 % of the predicted C. elegans genes are designated as proteases in the Merops protease database
(http://merops.sanger.ac.uk). The largest class are the metalloproteases, which includes the M1 aminopeptidase family (EC. 3.4.11.2) responsible for cleavage of N-terminal amino acid residues from peptide substrates. Aminopeptidases have been shown to have a plethora of roles in biology and disease, including, embryogenesis, reproduction, neuropeptide processing, antigen presentation, inflammation and cancer. There is however limited information on aminopeptidase functions in nematodes. Sequence analyses of the C. elegans gene T07F10.1 predicts that it encodes a membrane-associated aminopeptidase that is functional, based upon the presence of the HEXXH(X)18E metal ion coordination site and the GAMEN motif. Phylogenetic analysis shows that T07F10.1 is the homologue of the highly immunogenic Haemonchus contortus H11 'hidden antigen'. The expression pattern of T07F10.1 was studied by generating transgenic C. elegans expressing GFP under the control of the T07F10.1 promoter region. The T07F10.1::GFP reporter gene was expressed post-embryonically in the excretory cell and also in neurons of the pre-anal ganglia and tail, suggesting potential roles in osmoregulation, excretion, detoxification and neurobiology. A T07F10.1 deletion mutant, RB804, has been obtained from the C. elegans gene knock-out consortium. Sequence analysis has shown that the gene deletion is 1150 bp in size, truncating the protein and removing essential active site residues from the aminopeptidase. Phenotypic analysis of RB804 is in progress.