The present invention relates to a brain delivery protein, comprising a target binding antibody which binds to a target in a mammalian brain； two carrier moieties, each of which being capable of monovalent interaction with a protein expressed on a blood brain barrier (BBB) endothelial cell, wherein each of said carrier moieties is linked to a C-terminal end of the target binding antibody. The present invention moreover relates to use of such brain delivery proteins in therapy or diagnosis or for research of e.g. neurodegenerative disorders, and other brain diseases.
