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ISRN Cell Biology
Volume 2013 (2013), Article ID 265182, 16 pages
http://dx.doi.org/10.1155/2013/265182
Research Article

Identification of PDZ Domain Containing Proteins Interacting with 1.2 and PMCA4b

1Institute of Physiology, University of Wuerzburg, Roentgenring 9, 97070 Wuerzburg, Germany
2Eye Clinic, University of Regensburg, Franz-Josef-Strauss-Allee 11, 93042 Regensburg, Germany
3Department of Medicine I, University of Wuerzburg, Oberduerrbacherstraße 4, 97080 Wuerzburg, Germany

Received 30 November 2012; Accepted 25 December 2012

Academic Editors: T. Yazawa, N. Zambrano, and Y. Zhang

Copyright © 2013 Doreen Korb et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

PDZ (PSD-95/Disc large/Zonula occludens-1) protein interaction domains bind to cytoplasmic protein C-termini of transmembrane proteins. In order to identify new interaction partners of the voltage-gated L-type Ca2+ channel 1.2 and the plasma membrane Ca2+ ATPase 4b (PMCA4b), we used PDZ domain arrays probing for 124 PDZ domains. We confirmed this by GST pull-downs and immunoprecipitations. In PDZ arrays, strongest interactions with 1.2 and PMCA4b were found for the PDZ domains of SAP-102, MAST-205, MAGI-1, MAGI-2, MAGI-3, and ZO-1. We observed binding of the 1.2 C-terminus to PDZ domains of NHERF1/2, Mint-2, and CASK. PMCA4b was observed to interact with Mint-2 and its known interactions with Chapsyn-110 and CASK were confirmed. Furthermore, we validated interaction of 1.2 and PMCA4b with NHERF1/2, CASK, MAST-205 and MAGI-3 via immunoprecipitation. We also verified the interaction of 1.2 and nNOS and hypothesized that nNOS overexpression might reduce Ca2+ influx through 1.2. To address this, we measured Ca2+ currents in HEK 293 cells co-expressing 1.2 and nNOS and observed reduced voltage-dependent 1.2 activation. Taken together, we conclude that 1.2 and PMCA4b bind promiscuously to various PDZ domains, and that our data provides the basis for further investigation of the physiological consequences of these interactions.