Retinol-binding protein

Retinol-binding protein (RBP) are carrier proteins which bind retinol (vitamin A alcohol). Human RBP4 is the carrier of retinol in the blood. It delivers retinol from the liver to the peripheral tissues. RBP also functions in regulation, metabolism and activities of retinoids. Retinol is being protected from oxidation and becomes soluble when bound to RBP. RBP is used to assess vitamin A deficiency as it binds 1:1 to retinol. RBP is classified according to its site of activity. Plasma RBP (PRBP) carries retinol in blood while cellular RBP (CRBP) carries retinol in the cell.

3D structures of retinol-binding protein3D structures of retinol-binding protein

Plasma RBP (PRBP)

1rbp, 1jyd - hRBP – human 1jyj - hRBP (mutant) 1aqb - RBP – pig

Cellular RBP (CRBP)

1jbh, 1kgl, 1mx7 - rRBP I – NMR
1b4m - rRBP II – rat – NMR
2rcq - hRBP II
1ggl - hRBP III
1lpj - hRBP IV
[[1kqx – ZeRBP – zebrafish

Plasma RBP complex

3bsz - hRBP II + transthyretin + antibody + retinol
3fmz - hRBP IV + non-retinoid ligand
2wq9 - hRBP IV + oleate
2wq9 - hRBP IV + linoleate
2wqa - hRBP IV + transthyretin + oleate
1iiu - RBP + retinol – chicken
1kt3, 1kt4, 1kt5, 1kt6, 1kt7 - RBP + retinol – bovine

Cellular RBP complex

1mx8 - rRBP I + retinol – NMR
1eii - rRBP II + retinol – NMR
2rct - hRBP II + retinol
1kqw - ZeRBP + retinol