Fig. 7.

Model for relationship between PRs and MCs. MCs are PK-deficient, so glycolytic intermediates can be used for anabolic activities. MCs are AGC1-deficient, so mitochondrial oxaloacetate in MCs is not diverted away from the pathway that leads to Gln synthesis. To compensate for these metabolic deficiencies, PRs produce Lac that MCs can oxidize to Pyr to fuel their mitochondria. PRs also export Asp that MCs can use to oxidize Lac. Nitrogen for the amino group of Gln comes from Asp, and nitrogen for the amide group of Gln comes from NH₄⁺. Mal, malate; OAA, oxaloacetate; OGC, oxoglutarate carrier; Succ, succinate. Double-membrane compartments within the cells represent mitochondria. Green circles represent Glu, and green cylinders represent Glu receptors.