Davidson College 1 article published in JoVE Biochemistry Expression, Solubilization, and Purification of Eukaryotic Borate Transporters Sebastian Flores1, Andrew P. Feld1, Bryan H. Thurtle-Schmidt1 1Department of Biology, Davidson College Here we present a protocol to express, solubilize, and purify several eukaryotic borate transporters with homology to the SLC4 transporter family using yeast. We also describe a chemical cross-linking assay to assess the purified homomeric proteins for multimeric assembly. These protocols can be adapted for other challenging membrane proteins.