Guanine nucleotide exchange factor (GEF); which can activate some; but not all; G-alpha proteins independently of G- protein coupled receptors. Acts by exchanging bound GDP for free GTP. Able to facilitate synaptic transmission in the nervous system probably by activating G(q)-alpha (egl-30). Also able to activate the G(s)-alpha in synaptic signaling network. Plays a key role in asymmetric spindle positioning; a step for asymmetric cell division that generates cell diversity during development by activating G(i)-alpha protein goa-1 and gpa-16 independently of G- protein coupled receptors. While it acts as a GEF for goa-1; it has no GEF activity toward gpa-16. In addition to its GEF activity; it is required for cortical subcellular localization of G-alpha proteins such as gpa-16. Also required for the interaction of goa-1 and gpr-1/2; suggesting that it may act by generating G- alpha proteins free from G-beta-gamma subunits; enabling gpr-1/2 to mediate asymmetric cell division. {ECO:0000269|PubMed:11102364; ECO:0000269|PubMed:15479638; ECO:0000269|PubMed:15479639; ECO:0000269|PubMed:15489510; ECO:0000269|PubMed:15489511; ECO:0000269|PubMed:15498497; ECO:0000269|PubMed:16162648; ECO:0000269|PubMed:9851916}.