Diacylglycerol (DAG) plays a central role in both the synthesis of complex lipids and in 
intracellular signaling; diacylglycerol 
kinase (DGK) catalyzes the 
phosphorylation of DAG, which yields 
phosphatidic acid. A family of DGKs has been identified in multicellular organisms over the past few years, but the 
physiological function(s) of this diversity is not clear. One clue has come from the Drosophila DGK2, rdgA, since mutations in this 
gene cause 
retinal degeneration. The present invention relates to a novel DGK, designated DGKι, which was isolated from human 
retina and brain libraries. DGKι contains two 
cysteine-rich repeats, a region similar to the 
phosphorylation site domain of MARCKS, a conserved catalytic domain, and four 
ankyrin repeats at its C-terminus. By primary structure, DGKι is most similar to human DGKζ and Drosophila rdgA. A>12 kb mRNA for DGKι was detected only in brain and 
retina among the tissues examined. In cells transfected with the DGKι cDNA, an approximately 130 kDa 
protein was detected by 
immunoassay, and activity assays demonstrated that it encodes a functional DAG 
kinase. The 
protein was found to be in both the 
cytoplasm and 
nucleus, with this localization controlled by PKC isoforms alpha and gamma. The 
gene encoding DGKι was localized to human 
chromosome 7q32.3-33, which is known to be a locus for an inherited form of 
retinitis pigmentosa. These results have defined a novel isoform of DAG 
kinase, which may have important 
cellular functions in the 
retina and brain.