Key enzyme in the regulation of glycerol uptake and metabolism. Essential for male fertility and sperm mitochondrial sheath formation (By similarity). Required for proper arrangement of crescent-like mitochondria to form the mitochondrial sheath during spermatogenesis (By similarity). Can induce mitochondrial clustering through interactions with PLD6 and up-regulation of phosphatidic acid synthesis in the mitochondria (PubMed:28852571). ATP + glycerol = ADP + H(+) + sn-glycerol 3-phosphate Polyol metabolism; glycerol degradation via glycerol kinase pathway; sn-glycerol 3-phosphate from glycerol: step 1/1. Interacts with ARMC12 (By similarity). Interacts with PLD6 (PubMed:28852571). In sperm the majority of the enzyme is bound to mitochondria. Testis-specific (PubMed:33536340). Expressed in the midpiece of spermatozoa (PubMed:28852571). Belongs to the FGGY kinase family.