Enables ubiquitin protein ligase activity. Involved in regulation of gene expression. Located in cytoplasm and nuclear periphery. Colocalizes with polytene chromosome. Is expressed in several structures, including adult brain cell body rind; embryonic/larval midgut primordium; presumptive embryonic/larval central nervous system; and synaptic neuropil domain. Used to study central nervous system disease and neurodevelopmental disorder with regression, abnormal movements, loss of speech, and seizures. Human ortholog(s) of this gene implicated in common variable immunodeficiency 14 and neurodevelopmental disorder with regression, abnormal movements, loss of speech, and seizures. Orthologous to several human genes including IRF2BP1 (interferon regulatory factor 2 binding protein 1) and IRF2BPL (interferon regulatory factor 2 binding protein like).