The bilirubin transporter (bilitranslocase; BLT) of 340 aas and 3 or 4 TMSs. A structural model has been proposed (Roy Choudhury et al. 2015).  Strangely, no homologues are present in the NCBI protein database as of September, 2019, even from another mammal. A possible distant homologue is a hypothetical protein AUH14_01145 of 333 aas and 1 - 3 TMSs, the Candidatus Rokubacteria bacterium 13_2_20CM_69_15_1] (ACCESSION # OLB08456).  Structural analyses of TMSs in different micellar environments have been published (Szutkowski et al. 2019).