The invention relates to a peptide, polypeptide, or protein that binds specifically to cells of the lung endothelium. The peptide, polypeptide, or protein can be a component of a viral capsid and can be used to lead a recombinant viral vector selectively to the lung endothelial tissue after systemic administration to a subject and to ensure tissue-specific expression of one or more transgenes there. The invention thus further relates to a recombinant viral vector, preferably an AAV vector, which comprises a capsid comprising the peptide, polypeptide, or protein according to the invention and which comprises at least one transgene packaged in the capsid. The viral vector is suitable in particular for the therapeutic treatment of a lung disorder or a lung disease. The invention further relates to cells and pharmaceutical compositions which comprise the viral vector according to the invention.