Faculty Sponsor: Bryan Thurtle-Schmidt
The SLC4 family of membrane transporters includes Anion Exchanger 1, also known as Band 3, the most abundant membrane protein in human red blood cells. Whereas Band 3 transports bicarbonate, other SLC4 family proteins in plants and fungi are responsible for transport of borate. Borate is toxic at high enough levels within plants and yeast, and borate transport in plants and fungi is crucial for survival. Bicarbonate transport across red blood cell membranes is crucial for the regulation of carbon dioxide transport throughout the body. Insights into the structure of borate transporters help to better understand bicarbonate transport in human red blood cells. It remains a challenge to purify low expressing membrane proteins well enough for structural studies. It also remains unknown which amino acids are responsible for substrate binding in SLC4 proteins. Here we outline procedures for purification of borate transporters and the structural characterization of their dimeric status. An introduction into the isothermal titration calorimetry (ITC) data outlines possible insights we may be able to deduce from understanding binding differences between mutant and native transporters. Insights from these studies collectively assist with the understanding of structure/ function relationships present in SLC4 family transporters.