Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2011 Apr;137(4):385-90.
doi: 10.1085/jgp.201110596. Epub 2011 Mar 14.

Lysosomal pH and analysis of the counter ion pathways that support acidification

Jessica E DiCiccio  1 , Benjamin E Steinberg
Affiliations

Lysosomal pH and analysis of the counter ion pathways that support acidification

Jessica E DiCiccio et al. J Gen Physiol. 2011 Apr.
No abstract available

PubMed Disclaimer

Figures

Figure 1.
Figure 1.
Determinants of lysosomal pH. Lysosomal acidification is dependent on V-ATPase, a large multimeric enzyme complex that transforms the energy of ATP hydrolysis into the movement of protons across the lysosome membrane. Electrogenic proton transport creates an electrical gradient that must be dissipated to establish the substantial chemical proton gradient. Electroneutrality can be maintained through the parallel influx of anions alongside protons. ClC-7, a chloride proton antiporter, and CFTR have been proposed to constitute the counter ion pathways in the lysosome membrane, as described in the text. The efflux of cations (C+) through distinct channels or transporters can also occur. Parallel proton leak pathways (dotted lines) are also known to exist and require continued V-ATPase activity to maintain a steady-state pH. Acidification kinetics are also contingent on the luminal buffering power (not depicted).
Figure 2.
Figure 2.
Ratiometric pH measurements. (A) pH sensitivity of the excitation spectra of Oregon Green (OG)-labeled dextran between pH 4.0 and 8.0. The arrows indicate the wavelengths used to construct a ratiometric pH titration curve. (B) In vitro pH titration of OG dextran (green squares) and fluorescein-TMR (F-TMR) dextran (red diamonds). The normalized excitation fluorescence intensity ratio of 490:440 nm and 490:550 nm are plotted for the OG dextran and F-TMR dextran, respectively. The gray bar indicates the range of recently reported lysosome pH values (Christensen et al., 2002; Trombetta et al., 2003; Kasper et al., 2005; Lange et al., 2006; Poët et al., 2006; Tabeta et al., 2006; Haggie and Verkman, 2007). (C) Macrophage lysosomes were loaded with either OG dextran (left) or F-TMR dextran (right), and their pH clamped at pH 7.4 using ionophores before repeated illumination of the sample. For the OG dextran, the normalized fluorescence intensity of the 490-nm (dotted green) and the 440-nm (blue) channels are shown along with the 490:440 nm ratio (black). F-TMR was imaged in both the FITC (dotted green) and TMR (red) channels, with the FITC/TMR ratio given by the black line. The latter is unstable even in conditions of constant pH because of the differential photobleaching of the FITC and TMR. This is in contrast to the intramolecular ratio of OG that remains uniform.
See this image and copyright information in PMC

References

    1. Barriere H., Bagdany M., Bossard F., Okiyoneda T., Wojewodka G., Gruenert D., Radzioch D., Lukacs G.L. 2009. Revisiting the role of cystic fibrosis transmembrane conductance regulator and counterion permeability in the pH regulation of endocytic organelles. Mol. Biol. Cell. 20:3125–3141 10.1091/mbc.E09-01-0061 - DOI - PMC - PubMed
    1. Christensen K.A., Myers J.T., Swanson J.A. 2002. pH-dependent regulation of lysosomal calcium in macrophages. J. Cell Sci. 115:599–607 - PubMed
    1. Deriy L.V., Gomez E.A., Zhang G., Beacham D.W., Hopson J.A., Gallan A.J., Shevchenko P.D., Bindokas V.P., Nelson D.J. 2009. Disease-causing mutations in the cystic fibrosis transmembrane conductance regulator determine the functional responses of alveolar macrophages. J. Biol. Chem. 284:35926–35938 10.1074/jbc.M109.057372 - DOI - PMC - PubMed
    1. Di A., Brown M.E., Deriy L.V., Li C., Szeto F.L., Chen Y., Huang P., Tong J., Naren A.P., Bindokas V., et al. 2006. CFTR regulates phagosome acidification in macrophages and alters bactericidal activity. Nat. Cell Biol. 8:933–944 10.1038/ncb1456 - DOI - PubMed
    1. Doherty G.J., McMahon H.T. 2009. Mechanisms of endocytosis. Annu. Rev. Biochem. 78:857–902 10.1146/annurev.biochem.78.081307.110540 - DOI - PubMed

Publication types

Substances