Catalyzes the first step in phosphatidylcholine biosynthesis. May contribute to phosphatidylethanolamine biosynthesis. Phosphorylates choline and ethanolamine but the activity is much higher with choline. ATP + choline = ADP + H(+) + phosphocholine ATP + ethanolamine = ADP + H(+) + phosphoethanolamine Mn(2+) is a poor substitute (PubMed:12758145). Inhibited by Ca(2+). Mild inhibition by high levels of Mg(2+)(>10 mM) (PubMed:14960577). Optimum pH is 10. Phospholipid metabolism; phosphatidylcholine biosynthesis; phosphocholine from choline: step 1/1. Phospholipid metabolism; phosphatidylethanolamine biosynthesis; phosphatidylethanolamine from ethanolamine: step 1/3. Homodimer (PubMed:12791258, PubMed:12758145). A small proportion exists as higher oligomers (PubMed:12758145). Belongs to the choline/ethanolamine kinase family.