The yellow-red color cocoon formation of Bombyx mori is due to the selective delivery of carotenoids from midgut lumen into silk gland,and is thought to be mediated by specific cellular carotenoids carrier proteins.Previous researches have determined that CBP and Cameo2 are the products of the yellow blood (Y) gene and the yellow cocoon (C) gene of silkworm,respectively.In the yellow cocoon variety,they are mainly responsible for the selective delivery of lutein into middle silkgland.As CBP and Cameo2 are expressed in the same tissues of the larval body of the C allele strain with the background of the Y allele and the Y gene is also involve in the absorption of other carotenoids such as β-carotene from the midgut lumen into midgut mucosal cells,speculating that the selective delivery of carotenoids to specific tissues might requires the combined action of CBP and Cameo2.In order to prove the postulation and make clear their respective contribution in the cellular transport of carotenoids.The interrelation between the type and content of carotenoids and the gene expressing of CBP and Cameo2 in different tissues from four silkworm varieties producing different color cocoons were investigated.As the same time,the contribution of CBP and Cameo2 in cellular carotenoids uptake was researched in cell lines.The results show that CBP and Cameo2 genes were expressed simultaneously only in the tissues accumulating large amounts of lutein.Cells co-expressing CBP and Cameo2 can absorb higher lutein than the control group and the cells expressing single protein group,differences are very significant (P<0.01),and the cellular uptake of lutein was concentration-dependent and saturation.Furthermore Cameo2 and CBP were located in different region of the cells,the former was localized at the plasma membrane,and the latter in the entire cells.Bimolecular fluorescence complementation (BiFC) analysis showed that there was potential interaction between CBP and Cameo2 in the area near the plasma membrane.We hypothesize that the plasma membrane protein Cameo2 can identify and capture lutein from micelles in culture medium.the cytoplasmic protein CBP might interact directly with intracellular part of Cameo2 to co-mediate lutein but not β-carotene from the extracellular into the intracellular.