Transports CMP-sialic acid from the cytosol into the Golgi apparatus, functioning as an antiporter that exchanges CMP-sialic acid for CMP ( ). Binds both CMP-sialic acid and free CMP, but has higher affinity for free CMP (By similarity). Also able to exchange CMP-sialic acid for AMP and UMP . Also mediates the transport of CDP-ribitol (By similarity).
Subcellular locations: Golgi apparatus membrane, Golgi apparatus