Guanine nucleotide-binding proteins (G proteins) are involved as modulators or transducers in various transmembrane signaling systems. In the 1-cell embryo, probably together with goa-1, controls nuclear rotation and spindle elongation during mitosis (PubMed:14534135). During the first embryonic cell divisons, plays a role in gpr-1/2 cortical localization and in the proper orientation of EMS blastomere mitotic spindle (PubMed:14534135). G proteins are composed of 3 units; alpha, beta and gamma. The alpha chain contains the guanine nucleotide binding site. Simultaneous RNAi-mediated knockdown of both gpa-16 and goa-1 causes, in the one-cell embryo, a lack of nuclear rocking movements from prophase to metaphase and symmetric spindle elongation without transversal oscillations of the poles during anaphase. At the 2-cell stage embryo, nuclei are mispositioned and fail to exhibit nuclear rotation. In addition, causes a loss of gpr-1/2 cortical localization in 2-cell and 4-cell stage embryos. Belongs to the G-alpha family.