SOVEREIGN · INQ·12

M4 · The Selective Border

Two membranes, one rule: the mitochondrion admits a pre-processed fragment — pyruvate — but never glucose itself.

Drag a molecule at the border

Glucose~180 Da · 6-C

Pyruvate~88 Da · 3-C

Grab a chip → drag it down through the membranes toward the matrix. Watch what happens at the inner membrane.

Cytosolic NADH · electron shuttle

Live border log

Outer membraneporous · VDAC open

Inner membraneselective · sealed

Pyruvate routeMPC1 / MPC2

NADH e⁻ routemalate–aspartate

Last event— idle —

The mitochondrion receives pyruvate, not glucose. Inner-membrane selectivity forces every workaround.

Legend

Glucose / pyruvate — carbon fuel (amber)

Electrons (NADH) — cyan cargo the shuttle hands across

VDAC — outer-membrane porin, small molecules pass freely

MPC — the only door for pyruvate (inner membrane)

Inner membrane — the real barrier; blocks glucose & NADH