The desA gene of the cyanobacterium Synechocystis sp. strain PCC6803 is the structural gene for delta 12 desaturase.

The desA gene of the cyanobacterium Synechocystis sp. strain PCC6803 was expressed in Escherichia coli, which does not contain any fatty acid desaturase. The product of the desA gene catalyzed the desaturation of fatty acids at the delta 12 position. This result demonstrates that desA is the structural gene for a delta 12 desaturase.