BEST1

xCT is a sodium independent glutamate transporter that regulates the exchange of extracellular l-cystine and intracellular l-glutamate across the plasma membrane. This process is critical to glutathione production and protection from subsequent oxidative stress.

RANKL (also known as TNF-related activation-induced cytokine), or receptor activator of nuclear factor-κB ligand, was first discovered as a key player in the RANKL/RANK/OPG osteoclast formation pathway.

The human Bestrophin family has four members, Best1, Best2, Best3 and Best4. These transmembrane proteins can function as chloride channels, and can also regulate calcium channels (1). The Bestrophins all have a conserved domain which begins at the N-terminus and is predicted to contain four transmembrane regions; the highly variable cytosolic domain, which follows the fourth transmembrane region, distinguishes the family members from one another (2).

Encoded by the VMD2 gene on chromosome 11q13 Bestrophin 1 is the prototypic member of the RFP family of proteins which are more commonly called "bestrophins". The protein family was originally identified in Caenorhabditis elegans based on a conserved amino acid motifs Arg-Phe-Pro (RFP). In humans there are four members of the bestrophin family numbered sequentially BEST1, BEST2, BEST3 and BEST4.