Based on limited published evidence, RNF133 is an E3 ubiquitin-protein ligase localized to cytoplasm, endoplasmic reticulum, Golgi apparatus, and late endosomes. It participates in ubiquitin-dependent protein catabolic processes and plays a role in male fecundity through interaction with E2 ubiquitin-protein ligase UBE2J1 1. RNF133 expression is significantly reduced during spermatogenesis in GRTH-deficient mice, suggesting involvement in histone ubiquitination and spermatid development 2. A novel RNF133 variant was identified as a candidate risk gene for autism spectrum disorder 3.