Lysosomal membrane chaperone required to export cobalamin (vitamin B12) from the lysosome to the cytosol, allowing its conversion to cofactors. Targets ABCD4 transporter from the endoplasmic reticulum to the lysosome. Then forms a complex with lysosomal ABCD4 and cytoplasmic MMACHC to transport cobalamin across the lysosomal membrane (By similarity). May play a role in mediating and regulating the internalization of the insulin receptor (By similarity). Belongs to the LIMR family. LMBRD1 subfamily.