The neuronal calcium sensor (NCS) proteins belong to a subfamily of the EF-hand calcium binding proteins. These proteins are primarily expressed in the nervous system and currently include more than 20 members across species [Nakayama et al., J Mol Evol 34:416-448, 1992]. Two homologues of the ncs genes, Ce-ncs-1
, have recently been identified in the nematode C. elegans. Here we report the cDNA sequence of a third C. elegans ncs homologue, Ce-ncs-3
. We demonstrate that a null mutation in this gene caused by a large deletion in the locus does not confer a visible phenotype in C. elegans. This, in addition to the strong homology between Ce-NCS-3 and the other C. elegans NCS proteins, may indicate functional redundancy between the three genes.