Catalysis of the reaction: cytolipin-H + CMP-N-acetylneuraminate = alpha-N-acetylneuraminyl-2,3-beta-D-galactosyl-1,4-beta-D-glucosylceramide + CMP. Alpha-N-acetylneuraminyl-2,3-beta-D-galactosyl-1,4-beta-D-glucosylceramide is also known as GM3.
cytidine monophosphoacetylneuraminate-lactosylceramide sialyltransferase