Functional Properties of Organic Cation Transporter OCT1, Binding of Substrates and Inhibitors, and Presumed Transport Mechanism

Koepsell, Hermann; Keller, Thorsten

doi:10.1007/978-3-319-23793-0_2

Cited by 2 publications

(8 citation statements)

References 68 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The OCT2 total cell expression-based predicted metformin CL r,sec was corrected as follows: 1) the percent of OCT2 expressed in the plasma membrane in OCT2-expressing cells and 2) the difference in plasma membrane potential between HEK293/MDCKII cells and human renal epithelial cells. The latter was based on the observations by Burt et al (2016) and Koepsell and Keller (2016). The rate of OCT2-mediated metformin transport was directly proportional to the difference in electrochemical driving force across the plasma membrane of OCT2-expressing cells and kidney epithelial cells (Burt et al, 2016;Koepsell and Keller, 2016).…”

Section: Determination Of Percent Plasma Membrane Expression Of Oct2 Inmentioning

confidence: 99%

“…The latter was based on the observations by Burt et al (2016) and Koepsell and Keller (2016). The rate of OCT2-mediated metformin transport was directly proportional to the difference in electrochemical driving force across the plasma membrane of OCT2-expressing cells and kidney epithelial cells (Burt et al, 2016;Koepsell and Keller, 2016). We assumed that both HEK293 and MDCKII cells had a similar resting membrane potential difference of 235 mV (see Discussion for details).…”

Section: Determination Of Percent Plasma Membrane Expression Of Oct2 Inmentioning

confidence: 99%

See 1 more Smart Citation

The Importance of Incorporating OCT2 Plasma Membrane Expression and Membrane Potential in IVIVE of Metformin Renal Secretory Clearance

et al. 2018

View full text Add to dashboard Cite

Transporter expression, determined by quantitative proteomics, together with PBPK models is a promising approach for in vitro-to-in vivo extrapolation (IVIVE) of transporter-mediated drug clearance. OCT2-expressing HEK293 and MDCKII cells were used to predict in vivo renal secretory clearance (CL) of metformin. [C]-Metformin uptake clearance in OCT2-expressing cells was determined and scaled to in vivo CL by using OCT2 expression in the cells versus the human kidney cortex. Through quantitative targeted proteomics, the total expression of OCT2 in HEK293, MDCKII cells, and human kidney cortex was 369.4 ± 26.8, 19 ± 1.1, and 7.6 ± 3.8 pmol/mg cellular protein, respectively. The expression of OCT2 in the plasma membrane of HEK293 and MDCKII cells, measured using an optimized biotinylation method followed by quantitative proteomics, was 30.2% and 51.6%, respectively. After correcting for percent of OCT2 expressed in the plasma membrane and the resting membrane potential (millivolts) difference between the OCT2-expressing cells and the renal epithelial cells, the predicted CL of metformin was 250.7 ml/min, a value within the range of the observed CL of metformin. These data demonstrate the promise of using quantitative proteomics for IVIVE of transporter-mediated drug clearance and highlight the importance of quantifying plasma membrane expression of transporters and utilizing cells that mimic the in vivo mechanism(s) of transport of drugs.

show abstract

Section: Determination Of Percent Plasma Membrane Expression Of Oct2 Inmentioning

confidence: 99%

Section: Determination Of Percent Plasma Membrane Expression Of Oct2 Inmentioning

confidence: 99%

The Importance of Incorporating OCT2 Plasma Membrane Expression and Membrane Potential in IVIVE of Metformin Renal Secretory Clearance

et al. 2018

View full text Add to dashboard Cite

show abstract

“…The OCT1 protein is characterized by a pseudosymmetric structure, which is common for all members of the MFS. Both, the N-terminal and C-terminal part, comprise six transmembrane domains (Koepsell and Keller, 2016). There is a big extracellular loop between the first and second transmembrane helix in OCT1 containing putative glycosylation sites according to the motive N-X-S/T at position N71, N96, and N112 (X means any amino acid) (Zhang et al, 1997).…”

Section: List Of Figuresmentioning

confidence: 99%

“…PiPT (accession number A8N031) and human OCT1 (accession number O15245) show 2008). It is assumed that in order to initiate the translocation process, first a low affinity binding site needs to be occupied by the substrate (Gorbunov et al, 2008;Koepsell and Keller, 2016). The data of the study by Gorbunov et al also suggested that F483 and F486 are involved in the conformational change during the translocation process.…”

Section: Structure-to-function Relationships In Oct1mentioning

confidence: 99%

“…So far it could be shown that at least three transmembrane domains (the 5 th , 8 th , and 11 th ) are involved in conformational changes during translocation. The 5 th and the 8 th transmembrane domain are suggested to be involved in structural changes depending on the transported substrate, whereas the 11 th transmembrane domain is suggested to be involved in structural changes independent of the transported substrate (Egenberger et al, 2012;Koepsell and Keller, 2016). Site-directed mutagenesis experiments on rat Oct1 revealed that the amino acids F160 (TMD 2), W218 (TMD 4), Y222 (TMD 4), T226…”

Section: Structure-to-function Relationships In Oct1mentioning

confidence: 99%

See 1 more Smart Citation

Functional characterization of genetic polymorphisms in the organic cation transporter OCT1 with a special focus on the substrate-specific effects of the M420del polymorphism

Seitz¹

View full text Add to dashboard Cite

Burckhardt and Prof. Viacheslav Nikolaev for their support and constructive discussions during our meetings that essentially contributed to this thesis. I am indebted to my supervisor Dr. Mladen Tzvetkov for his excellent scientific education, for his support at any time and his committed guidance throughout my entire thesis. Without his help and advice this work would not have been possible. Special thanks go to Prof. Hermann Koepsell and Prof. Thomas Mueller for their expertise in the field of transporters and their scientific support. Further I would like to thank Dr. Ralph Krätzner for his great support in protein modeling, Dr. Eva Wagner for her technical and methodical support concerning microscopy, and Prof. Beißbarth for performing the hierarchical clustering analyses. I would like to thank Sherin Pojar and Marleen Meyer for their collaboration and contribution to this thesis. Further, I would like to thank Dr. Kristin Bokelmann and Karoline Jobst for their technical assistance and supportive advice and experience throughout my work.Further, I would like to thank my colleagues from the Department of Clinical Pharmacology and all my friends and study colleagues for having an intense and great time and for all the experiences throughout the years. Especially I would like to thank Stefanie Meyer-Roxlau, Claudia Lüske, and Andreas Schraut for being such good friends and for cheering me up at any time. Moreover, I need to thank Brian Golat for making me laugh so hard. Our tea times made my days. Special thanks go to Jaroslav Morozov for our longlasting friendship and his odd sense of empathy that always cheers me up.To my dear family: Words cannot express the gratefulness I need to owe you. Thanks to my grandparents and my brother. My deepest gratitude goes to my parents for their any time support and for always being there for me. IX

show abstract

Functional Properties of Organic Cation Transporter OCT1, Binding of Substrates and Inhibitors, and Presumed Transport Mechanism

Cited by 2 publications

References 68 publications

The Importance of Incorporating OCT2 Plasma Membrane Expression and Membrane Potential in IVIVE of Metformin Renal Secretory Clearance

The Importance of Incorporating OCT2 Plasma Membrane Expression and Membrane Potential in IVIVE of Metformin Renal Secretory Clearance

Functional characterization of genetic polymorphisms in the organic cation transporter OCT1 with a special focus on the substrate-specific effects of the M420del polymorphism

Contact Info

Product

Resources

About