GK2 (glycerol kinase 2) is a mitochondrial enzyme with dual roles in glycerol metabolism and male fertility. In its metabolic function, GK2 catalyzes glycerol-3-phosphate biosynthesis and regulates glycerol uptake and metabolism. However, its primary physiological significance lies in spermatogenesis, where GK2 is essential for sperm mitochondrial sheath formation and male fertility 1. GK2 mediates mitochondrial clustering through interactions with PLD6 and phosphatidic acid synthesis upregulation in mitochondria. During spermiogenesis, GK2 is one of several proteins whose translation is selectively enhanced through METTL5-mediated 18S rRNA m6A modification, critical for proper sperm head and tail development 2. GK2 function requires post-translational S-depalmitoylation by the depalmitoylase ABHD10; loss of ABHD10-mediated depalmitoylation causes GK2 hyper-palmitoylation, leading to malformed mitochondrial sheaths and severe sperm motility defects 1. Mutations affecting GK2 expression or function contribute to oligoasthenoteratozoospermia (OAT), a major cause of male infertility 2. GK2's role in galactose metabolism appears minor compared to the predominant galactokinase GALK1 3. Clinically, GK2 dysfunction represents a genetic target for male infertility diagnosis and potential therapeutic intervention.