Involvement of other uptake transporters (e.g., OATP2B1, OATP1A2
, OAT2, and OAT7) and apical transporters (such as MATE1, MRP2, BCRP, and MDR1/3) could not be excluded.
Other TH secondary transporters include the aromatic amino acid transporter MCT10, the organic anion transporting polypeptide transporters (e.g., OATP1C1, OATP1A2
, and OPTP1A4), the large neutral amino acid transporters (LAT1 and LAT2), and another amino acid transporter, the L-cystine and L-glutamate exchanger.
In addition, OATP1A2
can also transport dehydroepiandrosterone sulfate, a precursor for the synthesis of steroid hormones .
Naringin is a major and selective clinical inhibitor of organic anion-transporting polypeptide 1A2 (OATP1A2
) in grapefruit juice.
OATP Signature sequence OATP1A2
D T R W V G A OATP1B1 D S R [W.bar] V G A OATP1B3 D S R W V G A OATP1C1 D P Q W V G A OATP2A1 D P R W I G A OATP2B1 D P R W V G A OATP3A1 D P R W I G A OATP4A1 S P L W V G A OATP4C1 D P R W L G A OATP5A1 D P R F I G N OATP6A1 S P E W L W T OATP Signature sequence OATP1A2
W W F G F L OATP1B1 [W.bar] [W.bar] L [N.bar] F L OATP1B3 W W L G F L OATP1C1 W W L G Y L OATP2A1 W W L G L L OATP2B1 W W L G F L OATP3A1 W W G G F L OATP4A1 W W V G F L OATP4C1 W W I G F L OATP5A1 W W S G F L OATP6A1 W W I N F L
Among the investigated uptake transporters, OATP1A2
was the only OATP transporter capable of fexofenadine uptake in intestine .
Previous in vitro studies showed that green tea catechins such as EGCG inhibited the activities of OATP1A2
and OATP2B1 which are expressed in the apical side of the intestinal epithelium in human (Roth et al.
Because of the structure and size of MCs, active uptake into cells occurs via organic anion-transporting polypeptides (OATP/Oatp), as confirmed for liver-specific human OATP1B1 and OATP1B3, mouse Oatp1b2 (mOatp 1b2), skate Oatp 1d1, and the more widely distributed OATP1A2
expressed, for example, at the blood--brain barrier.
Researchers also found that naringin appears to block a key drug uptake transporter, called OATP1A2
, which moves drugs from the small intestine to the bloodstream.
Canadian researchers found naringin appeared to block a molecule called OATP1A2
- which helps shuttle drugs into the bloodstream.
The best characterized family is the OATP1 family with three transporters OATP1A2
, OaTp1B1, and OATP1B3 that transport a number of typical OATP substrates including steroid hormone conjugates, thyroid hormones, prostaglandins, bile acids, and various drugs, for example, statins, antibiotics, and a number of anticancer drugs (for a review see ).
Within this concept, transporters from the OATP (SLC21) family such as OATp1A2
, OATP1B3, OATP2B1, and OATP3A1 contribute to the cellular accumulation of E1S [11, 12], while ABC-efflux pumps from the MRP-family (ABCC1 and ABCC2), and the breast-cancer resistance protein (BCRP, ABCG2) mediates the efflux of E1S from the cells  ( Figure 2).