The Evidence Layer for Scientific AI

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 Long Analysis Plan

Evidence Base for the Measurement Plan

Direct measurement of lysosomal Cl^- is enabled by three complementary approaches. First, whole-endolysosome patch-clamp on enlarged endolysosomes (Vacuolin-1, YM-201636, or Wortmannin + Latrunculin B in HEK293T cells) directly reports luminal chloride-dependent currents, with four recording configurations (endolysosome-attached, lumen-out, whole-endolysosome, cytosol-out) available to isolate luminal Cl^- contributions Protocol for assessing lysosomal ion channel function in mammalian cells using lysosomal patch-clamp technique [2026]. Second, ³⁶Cl concentrative uptake into purified lysosomes demonstrated high-level uptake driven by a proton gradient (internal 5 mM NaCl pH 4.0, external 5 mM Na³⁶Cl pH 7.0), confirming Cl^-/H⁺ antiport coupling Radiotracer evidence that ClC-7 mediates lysosomal Cl uptake. Third, DSF-derived binding affinities from SLC26A11 constrain the expected luminal Cl^- range to ~5–6 mM under acidic conditions SLC26A11 chloride binding affinity at lysosomal pH.

Computational Analysis Pipeline

• Electrophysiology fitting: Fit I-V curves from whole-endolysosome recordings to the Nernst/Goldman-Hodgkin-Katz framework to back-calculate luminal [Cl^-] from reversal potential shifts when luminal Cl^- is systematically varied. SLC26A11 reports Sf9 whole-cell currents of -114 ± 18 pA at -120 mV (baseline) and -833 ± 374 pA under acidification to pH 6.0, providing effect sizes for power calculations SLC26A11 current effect sizes under acidic conditions.
• Kinetic modelling: Use the ClC-7 2Cl^-:1H⁺ exchanger stoichiometry CLC exchanger stoichiometry review to simulate equilibrium [Cl^-]_lumen as a function of ΔpH using Nernst-derived electrochemical coupling equations in Python (scipy.integrate.odeint).
• Perturbation controls: Validate transporter identity with ClC-7/Ostm1 siRNA knockdown and squaramide-based synthetic transporters (SQ1/SQ2 at 10 μM) that dissipate lysosomal pH, confirming that measured Cl^- flux depends on endogenous antiporter function Squaramide Cl- transporters as lysosomal pH perturbation controls.

Known Limitations and Uncertainties

Pharmacological enlargement of endolysosomes may perturb membrane composition and regulatory proteins; selection bias favors larger vesicles; and the technique is operator-dependent Patch-clamp protocol limitations and biases. Direct in vivo luminal [Cl^-] calibration remains unresolved; the CLC review notes conflicting models for transport directionality under acidic pH and uncertain in vivo endosomal ion concentrations Uncertainty in in vivo vesicular chloride. What would disprove this framework: demonstrating that ClC-7 knockdown does not reduce measured lysosomal Cl^- uptake, or that luminal Cl^- is invariant across ΔpH conditions.