The complete family of genes encoding G proteins of Caenorhabditis elegans.

Caenorhabditis elegans is the first animal whose genomic sequence has been determined. One of the new possibilities in post-sequence genetics is the analysis of complete gene families at once. We studied the family of heterotrimeric G proteins. C. elegans has 20 Gα, 2 Gβ and 2 Gγ genes. There is 1 homologue of each of the 4 mammalian classes of Gα genes, Gi/Goα, Gsα, Gqα and G12α, and there are 16 new α genes. Although the conserved Gα subunits are expressed in many neurons and muscle cells, GFP fusions indicate that 14 new Gα genes are expressed almost exclusively in a small subset of the chemosensory neurons of C. elegans. We generated loss-of-function alleles using target-selected gene inactivation. None of the amphid-expressed genes are essential for viability, and only four show any detectable phenotype (chemotaxis defects), suggesting extensive functional redundancy. On the basis of functional analysis, the 20 genes encoding Gα proteins can be divided into two groups: those that encode subunits affecting muscle activity (homologues of Gi/Goα, Gsα and Gq; refs 3,4,5,6), and those (14 new genes) that encode proteins most likely involved in perception. [ABSTRACT FROM AUTHOR]