Calcineurin (CN), a protein phosphatase 2B (PP2B), is a serine/threonine phosphatase under the control of Ca 2+ /calmodulin. Calcineurin is a heterodimer of a catalytic and CaM-binding subunit, Calcineurin A, tightly bound to a Ca 2+ -binding regulatory subunit, Calcineurin B and two-subunit structure is conserved from yeast to human. It is well known that CN is a signaling molecule involved in various pathways in several types of tissues with a plethora of functions including T cell activation, cardiac hypertrophy, LTP, muscle remodeling, and development. The genome database predicted the genes encoding for both the catalytic and regulatory subunits in C. elegans on C02F4 and F55C10 (LG IV and V), respectively. We identified and characterized the two essential subunits for the CN homologue in C. elegans , we termed
cna-1 (calcineurin A) and
cnb-1 (calcineurin B). We found that
cna-1::gfp is expressed in neurons and muscles whereas
cnb-1::gfp shows more neuronal expression. Even though the expression of both genes was expected to co-localize, they showed slightly different expression patterns. Immunostaining using each polyclonal antibody show similar expression patterns of the proteins, which is in ventral nerve cord, gonad, spermatheca, and sperm. CNB-1 in C. elegans also has high capacity of Ca 2+ binding confirmed by a calcium overlay experiment. We performed a yeast two hybrid experiment and in vitro phosphatase assay in order to understand the interaction and role of the proteins in vivo and in vitro . These experiments showed that CNB-1 is necessary for the phosphatase activity, and the interaction between
cna-1 and
cnb-1 and the enzyme activity are Ca 2+ dependent. We have isolated and characterized a deletion mutant for
cnb-1 that displayed several phenotypic defects related with growth, body size, movement, brood size and sperm function. The various phenotypes seen in
cnb-1 mutants are consistent with the diverse functions that calcineurin as a signaling molecule plays roles in. In addition, since
tax-6 mutants that have a mutation in the calcineurin A gene show thermotaxic defects, we are testing whether the
cnb-1 deletion mutant also has any thermotaxic defects.