Table 1: Characteristics of pathways for cholesterol efflux from cells to plasma.

CharacteristicsAqueous diffusionSR-BIABCA1ABCG1

Energy requirementPassivePassive ActiveActive
Cholesterol fluxBidirectionalBidirectionalUnidirectionalUnidirectional
Preferred HDL acceptorsHDL2, HDL3HDL2, HDL3preβ-HDL
Lipid-poor/free apoA-I
HDL2, HDL3