Component of E3 ubiquitin ligase complex consisting of FBXO45, MYCBP2 and SKP1. Functions in substrate recognition but plays also an important role in assembly of the complex. Required for normal neuromuscular synaptogenesis, axon pathfinding and neuronal migration. Regulates neuron migration during brain development through interaction with N-cadherin/CDH2 after secretion via a non-classical mechanism. Plays a role in the regulation of neurotransmission at mature neurons. May control synaptic activity by controlling UNC13A via ubiquitin dependent pathway. Specifically recognizes TP73, promoting its ubiquitination and degradation. Polyubiquitinates NMNAT2, an adenylyltransferase that acts as an axon maintenance factor, and regulates its stability and degradation by the proteasome. Acts also by ubiquitinating FBXW7 during prolonged mitotic arrest and promotes FBXW7 proteasomal degradation. Induces subsequently an increase in mitotic slippage and prevents mitotic cell death. In response to influenza infection, mediates interferon-lambda receptor IFNLR1 polyubiquitination and degradation through the ubiquitin-proteasome system by docking with its intracellular receptor domain.