![Figure 3. Predicted lysosomal membrane potential. Simulations and color coding are identical to those described in Fig. 2 A for a model containing ClC-7 antiporters, a K+ carrier, and a minor proton leak, but no V-ATPases. The red curve was simulated with a high initial [K+]L (200 mM), the green curve with moderate [K+]L (30.6 mM), and blue curve with low [K+]L (5 mM). Initially, the membrane potential is enforced to be zero, but quickly becomes –45 mV, which stops ion transport via ClC-7 and brings the system to a steady state. Valinomycin was added at 16 s, at which point the potassium permeability was increased from 0 to 7.1 × 10−7 cm/s to account for this additional pathway. The membrane potential changed according to whether K+ exited or entered the lysosome. In all cases, the membrane potential remained negative during this period. FCCP was added at 63 s, which was modeled by increasing PH+ from 6 × 10−5 cm/s to 1 cm/s. This caused a spike in the membrane potential due to an inward flux of H+.](https://cdn.rupress.org/rup/content_public/journal/jgp/141/6/10.1085_jgp.201210930/6/jgp_201210930_fig3.jpeg?Expires=1773531598&Signature=SYUv5RnmESXeqvHCvL4AGJ9wLG0~mmhvcc9gBNuWZBVEeGAC7jH97GXBbGGdAET2SKJiL-4SmzZr~HvbUu5ZD7OEXjPZZTh~HM-NgrbMJzKg26sG9jiDnCE04mbTwrGigQe9wEmoYR5~WcbFylxcU8OWOlU7pVN2CIdvcc23G7BQFolEiFl23AS2P0j73YhfDuYJoV4Xq4UHEMZ3YK4iBhwugrsRdMTXfyjAXnua938oIfhwnRi1BnDVK9r4jUSVQ1wKX1PTH7sSfB2aZcvyXXQyUP9T-LE1r7fhuWxKsSpc4DU2Ibw2AnXSw93kiJGLqt2IBNaagSHES3a9y9efKA__&Key-Pair-Id=APKAIE5G5CRDK6RD3PGA)
Predicted lysosomal membrane potential. Simulations and color coding are identical to those described in Fig. 2 A for a model containing ClC-7 antiporters, a K+ carrier, and a minor proton leak, but no V-ATPases. The red curve was simulated with a high initial [K+]L (200 mM), the green curve with moderate [K+]L (30.6 mM), and blue curve with low [K+]L (5 mM). Initially, the membrane potential is enforced to be zero, but quickly becomes –45 mV, which stops ion transport via ClC-7 and brings the system to a steady state. Valinomycin was added at 16 s, at which point the potassium permeability was increased from 0 to 7.1 × 10−7 cm/s to account for this additional pathway. The membrane potential changed according to whether K+ exited or entered the lysosome. In all cases, the membrane potential remained negative during this period. FCCP was added at 63 s, which was modeled by increasing PH+ from 6 × 10−5 cm/s to 1 cm/s. This caused a spike in the membrane potential due to an inward flux of H+.
