Compositions and methods of using scorpion venom peptide that is a ligand for ABC transporters. One aspect provides a peptide having at least 80% sequence identity to SEQ ID NO: 1. The peptide Is believed to have a molecular mass of about 3.7 kDa and specifically interacts with cystic fibrosis transmembrane conductance regulator. Methods of treating a disorder or symptom of a disorder related to aberrant ABC transporter activity are also provided.
