Provided are vector compounds that bind to N-acetylated-alpha-linked acidic dipeptidase-like protein 2 (NAALADL2), and related conjugates, compositions, methods of use thereof, and methods of screening for and identifying the same, for instance, to facilitate delivery of therapeutic or diagnostic agents across the blood-brain barrier (BBB) and/or improve tissue penetration in CNS and peripheral tissues, and thereby treat and/or various diseases, including those of the central nervous system (CNS).