Plays a key role in phospholipid biosynthesis by catalyzing the phosphorylation of free choline to phosphocholine, the first step in phosphatidylcholine biosynthesis (PubMed:17007874, PubMed:19915674, PubMed:23416529, PubMed:34077757). Also phosphorylates ethanolamine, thereby contributing to phosphatidylethanolamine biosynthesis (PubMed:17007874, PubMed:19915674). Has higher activity with choline (PubMed:17007874, PubMed:19915674). May contribute to tumor cell growth (PubMed:19915674). {ECO:0000269|PubMed:17007874, ECO:0000269|PubMed:19915674, ECO:0000269|PubMed:23416529, ECO:0000269|PubMed:34077757}. [Isoform 1]: This isoform plays a key role in lipolysis of lipid droplets following glucose deprivation (PubMed:34077757). In response to glucose deprivation, phosphorylated by AMPK, promoting localization to lipid droplets (PubMed:34077757). Phosphorylation is followed by acetylation by KAT5, leading to dissociation of the homodimer into a monomer (PubMed:34077757). Monomeric CHKA isoform 1 is converted into a tyrosine-protein kinase, which phosphorylates lipid droplet structural proteins PLIN2 and PLIN3, leading to lipolysis of lipid droplets (PubMed:34077757). . This is the function of CHKA (choline kinase alpha, ENSG00000110721).