A Study of the Interaction Between the Basigin Transmembrane Domain and Monocarboxylate Transporter 1

It is thought that a lactate shuttle complex of Basigin gene products and Monocarboxylate transporter 1 (MCT1) is necessary for photoreceptor cell maturation and function. The purpose of this study was to investigate the assembly of the lactate shuttle by determining which amino acids within Basigin interact with MCT1. It has been hypothesized that these two membrane proteins interact via the transmembrane domain of Basigin. Therefore, a full-length histidine-tagged peptide of the transmembrane domain (24 amino acids), as well as histidine-tagged deletion mutants were generated using the pET1 02/0 vector (Invitrogen) to test for binding to MCT1 via enzyme-linked immunosorbent assay (ELISA). The probe containing the entire transmembrane domain of Basigin (amino acids 1 to 24) did interact with MCT1. An interaction was also observed when a probe containing amino acids 13 to 24 of the Basigin transmembrane domain was used. A comparable interaction was observed when amino acids 19 to 24 were used as a probe, but no signal was observed when amino acids 13 to 18 were used. This indicates that some or all of the six C-terminal amino acids of the Basigin transmembrane domain bind to MCT1. Site-directed mutagenesis of each of the six C-terminal amino acids, and subsequent ELISA analysis, . indicates that isoleucine - 20, isoleucine - 21, isoleucine - 23, and tyrosine - 24 interact with MCT1. Vlll