Diacylglycerol kinases (DGKs) phosphorylate diacylglycerol (DAG) to produce phosphatidic acid. DAG and phosphatidic acid are lipids that act as second messengers in signaling cascades. DGK-alpha influences cell activation and secretion of lethal exosomes, which in turn control cell death. DGK-beta is abundant in restricted brain regions such as the caudate putamen and olfactory tubercle. DGK-gamma encodes full-length and truncated transcripts that are present in a range of human tissues, with greatest expression observed in retina. DGK-delta is most abundant in skeletal muscle. DGK-epsilon shows specificity for arachidonyl-containing diacylglycerol and is expressed predominantly in testis. DGK-zeta is most abundant in brain and muscle. DGK-eta is closely related to DGK-delta. DGK-theta is most abundant in the cerebellum and hippocampus.