G protein of the Ras family that positively regulates phagocytosis and negatively regulates macropinocytosis (PubMed:9950684). May be involved in the activation of guanylyl cyclase during the response to hyperosmotic conditions (PubMed:12186953). Overexpressing cells generate alterations in cell shape and contractile responses (PubMed:12186953). Involved in chemotaxis via regulation of the balance of Ras and Rap signaling at the leading edge of chemotaxing cells (PubMed:27237792). GTP + H2O = GDP + H(+) + phosphate Interacts with ralGDS (only when rapA is in its GTP-bound state) (PubMed:12186953). Interacts with the Rap guanine nucleotide exchange factor glfB (PubMed:27237792). This protein is expressed at all stages during development but is expressed maximally during the aggregation and culmination periods. Null cells exhibit reduced viability in response to osmotic shock, reduced accumulation of cGMP in response to osmotic shock and decrease in growth rate. Belongs to the small GTPase superfamily. Ras family.