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Functional effects of caloxin 1c2, a novel engineered selective inhibitor of plasma membrane Ca(2+)-pump isoform 4, on coronary artery.

Pande J, Szewczyk MM, Kuszczak I, Grover S, Escher E, Grover AK - J. Cell. Mol. Med. (2008)

Bottom Line: Key properties of caloxin 1c2 are (a) Ki = 2.3 +/- 0.3 microM which corresponds to a 20x higher affinity for PMCA4 than that of caloxin 1b1 and (b) it is selective for PMCA4 since it has greater than 10-fold affinity for PMCA4 than for PMCA1, 2 or 3.We conclude that PMCA4 is pivotal to Ca(2+) extrusion in coronary artery smooth muscle.We anticipate caloxin 1c2 to aid in understanding the role of PMCA4 in signal transduction and home-ostasis due to its isoform selectivity and ability to act when added extracellularly.

View Article: PubMed Central - PubMed

Affiliation: Department of Biology, McMaster University, Hamilton, ON, Canada.

ABSTRACT
Coronary artery smooth muscle expresses the plasma membrane Ca(2+) pump (PMCA) isoforms PMCA4 and PMCA1. We previously reported the peptide inhibitor caloxin 1b1 that was obtained by using extracellular domain 1 of PMCA4 as the target (Am J Physiol Cell.290 [2006] C1341). To engineer inhibitors with greater affinity and isoform selectivity, we have now created a phage display library of caloxin 1b1-like peptides. We screened this library by affinity chromatography with PMCA from erythrocyte ghosts that contain mainly PMCA4 to obtain caloxin 1c2. Key properties of caloxin 1c2 are (a) Ki = 2.3 +/- 0.3 microM which corresponds to a 20x higher affinity for PMCA4 than that of caloxin 1b1 and (b) it is selective for PMCA4 since it has greater than 10-fold affinity for PMCA4 than for PMCA1, 2 or 3. It had the following functional effects on coronary artery smooth muscle: (a) it increased basal tone of the de-endothelialized arteries; the increase being similar at 10, 20 or 50 microM, and (b) it enhanced the increase in the force of contraction at 0.05 but not at 1.6 mM extracellular Ca(2+) when Ca(2+) extrusion via the Na(+)-Ca(2+) exchanger and the sarco/endoplasmic reticulum Ca(2+) pump were inhibited. We conclude that PMCA4 is pivotal to Ca(2+) extrusion in coronary artery smooth muscle. We anticipate caloxin 1c2 to aid in understanding the role of PMCA4 in signal transduction and home-ostasis due to its isoform selectivity and ability to act when added extracellularly.

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Caloxin 1c2 inhibition of PMCA Ca2+–Mg2+–ATPase in erythrocyte ghosts from different species.
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fig03: Caloxin 1c2 inhibition of PMCA Ca2+–Mg2+–ATPase in erythrocyte ghosts from different species.

Mentions: The sequence of the extracellular domain 1 differs slightly between human, pig and rabbit. Therefore, we tested the inhibition of PMCA Ca2+–Mg2+–ATPase in the erythrocyte ghosts from these species (Fig. 3). Caloxin 1c2 inhibited the Ca2+–Mg2+–ATPase with similar Ki values (in μM) in erythrocyte ghosts from human (2.3 ± 0.3), pig (2.6 ± 0.6) and rabbit (2.73 ± 0.5) (P > 0.05). Thus, caloxin 1c2 can be used for experiments in various species.


Functional effects of caloxin 1c2, a novel engineered selective inhibitor of plasma membrane Ca(2+)-pump isoform 4, on coronary artery.

Pande J, Szewczyk MM, Kuszczak I, Grover S, Escher E, Grover AK - J. Cell. Mol. Med. (2008)

Caloxin 1c2 inhibition of PMCA Ca2+–Mg2+–ATPase in erythrocyte ghosts from different species.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC4401146&req=5

fig03: Caloxin 1c2 inhibition of PMCA Ca2+–Mg2+–ATPase in erythrocyte ghosts from different species.
Mentions: The sequence of the extracellular domain 1 differs slightly between human, pig and rabbit. Therefore, we tested the inhibition of PMCA Ca2+–Mg2+–ATPase in the erythrocyte ghosts from these species (Fig. 3). Caloxin 1c2 inhibited the Ca2+–Mg2+–ATPase with similar Ki values (in μM) in erythrocyte ghosts from human (2.3 ± 0.3), pig (2.6 ± 0.6) and rabbit (2.73 ± 0.5) (P > 0.05). Thus, caloxin 1c2 can be used for experiments in various species.

Bottom Line: Key properties of caloxin 1c2 are (a) Ki = 2.3 +/- 0.3 microM which corresponds to a 20x higher affinity for PMCA4 than that of caloxin 1b1 and (b) it is selective for PMCA4 since it has greater than 10-fold affinity for PMCA4 than for PMCA1, 2 or 3.We conclude that PMCA4 is pivotal to Ca(2+) extrusion in coronary artery smooth muscle.We anticipate caloxin 1c2 to aid in understanding the role of PMCA4 in signal transduction and home-ostasis due to its isoform selectivity and ability to act when added extracellularly.

View Article: PubMed Central - PubMed

Affiliation: Department of Biology, McMaster University, Hamilton, ON, Canada.

ABSTRACT
Coronary artery smooth muscle expresses the plasma membrane Ca(2+) pump (PMCA) isoforms PMCA4 and PMCA1. We previously reported the peptide inhibitor caloxin 1b1 that was obtained by using extracellular domain 1 of PMCA4 as the target (Am J Physiol Cell.290 [2006] C1341). To engineer inhibitors with greater affinity and isoform selectivity, we have now created a phage display library of caloxin 1b1-like peptides. We screened this library by affinity chromatography with PMCA from erythrocyte ghosts that contain mainly PMCA4 to obtain caloxin 1c2. Key properties of caloxin 1c2 are (a) Ki = 2.3 +/- 0.3 microM which corresponds to a 20x higher affinity for PMCA4 than that of caloxin 1b1 and (b) it is selective for PMCA4 since it has greater than 10-fold affinity for PMCA4 than for PMCA1, 2 or 3. It had the following functional effects on coronary artery smooth muscle: (a) it increased basal tone of the de-endothelialized arteries; the increase being similar at 10, 20 or 50 microM, and (b) it enhanced the increase in the force of contraction at 0.05 but not at 1.6 mM extracellular Ca(2+) when Ca(2+) extrusion via the Na(+)-Ca(2+) exchanger and the sarco/endoplasmic reticulum Ca(2+) pump were inhibited. We conclude that PMCA4 is pivotal to Ca(2+) extrusion in coronary artery smooth muscle. We anticipate caloxin 1c2 to aid in understanding the role of PMCA4 in signal transduction and home-ostasis due to its isoform selectivity and ability to act when added extracellularly.

Show MeSH
Related in: MedlinePlus