Enables N-acetyllactosaminide alpha-2,3-sialyltransferase activity and beta-galactoside (CMP) alpha-2,3-sialyltransferase activity. Involved in positive regulation of blood coagulation and positive regulation of leukocyte tethering or rolling. Acts upstream of or within protein glycosylation. Predicted to be located in Golgi apparatus and membrane. Predicted to be integral component of membrane. Is expressed in several structures, including alimentary system; genitourinary system; hemolymphoid system; integumental system; and nervous system. Orthologous to human ST3GAL4 (ST3 beta-galactoside alpha-2,3-sialyltransferase 4). [provided by Alliance of Genome Resources, Apr 2022]