citrate3

Citrate3, also referred to as citrate synthase 3 (CIT3), is a member of the citrate synthase enzyme family. It catalyzes the condensation of acetyl-CoA and oxaloacetate to form citrate, the first step of the citric acid (TCA) cycle in aerobic metabolism.

In several fungal species, including some yeasts, CIT3 represents a distinct isoform within the citrate synthase gene family. The principal isoforms CIT1 and CIT2 are associated with mitochondria and peroxisomes, respectively; CIT3 is less conserved and can show different subcellular localization or regulation across species.

Localization and regulation vary: in some species the protein is predicted to localize to mitochondria, while in others it may be cytosolic. Expression of CIT3 can be responsive to carbon source, developmental stage, or environmental conditions, reflecting metabolic flexibility.

Biochemical properties: citrate synthases are typically homodimeric enzymes that initiate the TCA cycle by producing citrate from acetyl-CoA and oxaloacetate. CIT3 shares conserved catalytic motifs with other isoforms, though kinetic parameters and regulation can differ depending on localization and cellular context.

Importance: as a member of the citrate synthase family, CIT3 contributes to central carbon metabolism in fungi and can influence metabolic rerouting under nutrient limitation or stress. It is used as a model for isoform diversification and metabolic regulation and can impact industrial fermentation processes where citrate flux affects product yields.

See also: citrate synthase, CIT1, CIT2, glyoxylate cycle.