Key enzyme in the regulation of glycerol uptake and metabolism. Essential for male fertility and sperm mitochondrial sheath formation (PubMed:28852571, PubMed:30662012). Required for proper arrangement of crescent-like mitochondria to form the mitochondrial sheath during spermatogenesis.(PubMed:30662012). 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 PLD6 (PubMed:28852571). Interacts with ARMC12 (PubMed:33536340). In sperm the majority of the enzyme is bound to mitochondria. Testis-specific. Male mice are infertile due to dysfunctional spermatozoa, which exhibit unregulated ATP production, disordered mitochondrial sheath formation, abnormal mitochondrial morphology, and defective sperm tail (PubMed:30662012, PubMed:33536340). Spermatozoa cannot transit the uterotubal junction due to reduced motility leading to male infertility (PubMed:33536340). Spermatids exhibit abnormal arrangement of crescent-like mitochondria, which causes a disorganization of the mitochondrial sheath (PubMed:33536340). Belongs to the FGGY kinase family.