Amino acid residues in transmembrane domain 10 of organic anion transporting polypeptide 1B3 are critical for cholecystokinin octapeptide transport.
Amino acid residues in transmembrane domain 10 of organic anion transporting polypeptide 1B3 are critical for cholecystokinin octapeptide transport.
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DOI：
10.1021/bi8008455
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发表时间：
2008-09-02
期刊：
影响因子：
2.9
通讯作者：
Hagenbuch, Bruno
中科院分区：
文献类型：
--
作者：
Gui, Chunshan;Hagenbuch, Bruno
Human organic anion transporting polypeptides (OATP) 1B1 and 1B3 are multi-specific transporters that mediate uptake of amphipathic organic compounds into hepatocytes. The two OATPs contain twelve transmembrane domains (TMs) and share 80% amino acid sequence identity. Besides common substrates with OATP1B1, OATP1B3 specifically transports cholecystokinin octapeptide (CCK-8). To determine which structural domains/residues are important for the substrate selectivity of OATP1B3, we constructed a series of chimeric proteins between OATP1B3 and 1B1, expressed them in HEK293 cells and determined uptake of CCK-8 along with surface expression of the proteins. Replacing TM10 in OATP1B3 with TM10 of OATP1B1 resulted in dramatically reduced CCK-8 transport, indicating that TM10 is crucial for recognition and/or translocation of CCK-8. Using site-directed mutagenesis, we identified three key residues within TM10, namely Y537, S545 and T550. When we replaced these residues by the corresponding amino acid residues found in OATP1B1, CCK-8 transport was similarly low as for the replacement of the whole TM10. Kinetic experiments showedthat the Km values for CCK-8 transport in the TM10-replacement and triple mutant were only 1.3 and 1.1 μM, respectively as compared to 16.3 μM for wild-type OATP1B3. Similarly, the Vmax values dropped from 495.5 pmol/normalized mg/min for wild-type OATP1B3 to 13.3 and 19.0 for the TM10-replacement and triple mutant, respectively. Molecular modeling indicated that two of the three identified residues might form hydrogen bonds with CCK-8. In conclusion, we have identified three amino acid residues (Y537, S545 and T550) in TM10 of OATP1B3 that are important for CCK-8 transport.
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影响因子：
3.6
作者：
Smith, NF;Acharya, MR;Sparreboom, A
通讯作者：
Sparreboom, A
影响因子：
4.8
作者：
König, J;Cui, YH;Keppler, D
通讯作者：
Keppler, D
影响因子：
2.1
作者：
Morimoto, Kaori;Oishi, Tomoharu;Chiba, Kan
通讯作者：
Chiba, Kan
DOI：
10.1093/protein/8.2.127
发表时间：
1995-02-01
期刊：
PROTEIN ENGINEERING
影响因子：
--
作者：
WALLACE, AC;LASKOWSKI, RA;THORNTON, JM
通讯作者：
THORNTON, JM
影响因子：
4.8
作者：
Hsiang, BN;Zhu, YJ;Kirchgessner, TG
通讯作者：
Kirchgessner, TG