2.A.125.1.1
The riboflavin (Km = 40μM) transporter, RFT1, SLC52A1, of 448 aas and 11 TMSs in a 6 + 5 TMS arrangement (Yonezawa et al. 2008).  The C-terminal 150 aas are 92% identical to porcine endogenous retrovirus A receptor 2 (PERV-A receptor 2) and 57% identical to the G-protein-coupled receptor 172A (XP_001519123).RFT1 is also a viral receptor, and the putative structural and functional properties of the GHBh1 receptor have been summarized (Wolf et al. 2023). Vitamin B2/riboflavin transporters play key roles in biochemical oxidation-reduction reactions of carbohydrate, lipid, and amino acid metabolism (Yonezawa et al. 2008, Yao et al. 2010). It may function as a cell receptor for retroviral envelopes similar to the porcine endogenous retrovirus (PERV-A) (Ericsson et al. 2003). The SLC52 family includes RFVT1-3, mutations in which are associated with two diseases, MADD and the Brown-Vialetto-Van Laere syndrome (Ben Mariem et al. 2023).  Structure-function relationships have been reported (Ben Mariem et al. 2023).