Total and cell surface expression levels of HCA1, HCA2 and HCA3 orthologs as determined by ELISA.

Cell surface expression levels of mammalian HCAR orthologs were measured by a cell surface ELISA. Specific optical density (OD) readings are given as percentage of the respective HA-tagged human HCAR. The non-specific OD value (empty vector) was 0.014 ± 0.002 (set 0%). The OD value of the HA-tagged human HCA1 (0.091 ± 0.012), of the HA-tagged human HCA2 (0.755 ± 0.007) and of the HA-tagged human HCA3 (0.424 ± 0.038), each of which was set 100% to compare expression between orthologs. Total expression levels of mammalian HCAR orthologs were measured by a sandwich ELISA. Specific optical density (OD) readings are given as a percentage of HA-tagged respective human HCAR. The non-specific OD value (empty vector) was 0.011 ± 0.001 (set 0%). The OD value of the HA-tagged human HCA1 (0.057 ± 0.012), of the HA-tagged human HCA2 (0.591 ± 0.114) and of the HA-tagged human HCA3 (0.092 ± 0.006), each of which was set 100%. Data is given as mean ± SEM of three independent experiments carried out in triplicates.