Has a key role in phospholipid metabolism, and catalyzes the first step of phosphatidylethanolamine and phosphatidylcholine biosynthesis. ATP + choline = ADP + H(+) + phosphocholine ATP + ethanolamine = ADP + H(+) + phosphoethanolamine Phospholipid metabolism; phosphatidylethanolamine biosynthesis; phosphatidylethanolamine from ethanolamine: step 1/3. Homodimer, and heterodimer with CHKA. Expressed ubiquitously with the highest level in testis. Defects in Chkb are a cause of rostrocaudal muscular dystrophy (rmd). The disease is characterized by rapidly progressive muscular dystrophy and neonatal forelimb bone deformity. The dystrophy is only evident in skeletal muscle tissues in an unusual rostral-to-caudal gradient. Hindlimb muscular dystrophy. Hindlimb skeletal muscle tissue exhibits impaired phosphatidylcholine biosynthesis and increased phosphatidylcholine catabolism, with concomitant accumulation of choline. Mitochondria are abnormally large and exhibit decreased inner membrane potential. Belongs to the choline/ethanolamine kinase family.