Enables protein C-terminus binding activity and ubiquitin-protein transferase activity. Involved in neuron apoptotic process; protein destabilization; and ubiquitin-dependent protein catabolic process. Located in several cellular components, including cytosol; early endosome; and nucleus. Orthologous to human SIAH1 (siah E3 ubiquitin protein ligase 1). [provided by Alliance of Genome Resources, Apr 2022]