1 Département de Chimie, Université du Québec à Montréal, 2101, rue Jeanne-Mance, Montréal, QC, H2X 2J6, Canada.
2 Centre d'Excellence en Recherche sur les Maladies Orphelines - Fondation Courtois (CERMO-FC), Université du Québec à Montréal, Montréal, QC, H2X 3Y7, Canada.
3 Regroupement québécois de recherche sur la fonction, l'ingénierie et les applications des protéines (PROTEO), Montréal, QC, H3C 3P8, Canada.
4 Département des Sciences Biologiques, Université du Québec à Montréal, 141 avenue du Président-Kennedy, Montréal, QC, H2X 3X8, Canada.
5 Center for Studies in Behavioral Neurobiology, Concordia University, Montreal, QC, H4B 1R6, Canada.

Cellular trafficking between organelles is typically assured by short motifs that contact carrier proteins to transport them to their destination. Ubiquitin E3 ligase RING finger protein 13 (RNF13), a regulator of proliferation, apoptosis, and protein trafficking, localizes to endolysosomal compartments through the binding of a dileucine motif to clathrin adaptor protein complex AP-3. Mutations within this motif reduce the ability of RNF13 to interact with AP-3. Here, our study shows the discovery of a glutamine-based motif that resembles a tyrosine-based motif within RNF13's C-terminal region that binds to the clathrin adaptor protein complex AP-1, notably without a functional interaction with AP-3. Using biochemical, molecular, and cellular approaches in HeLa cells, our study demonstrates that a RNF13 dileucine variant uses an AP-1-dependent pathway to be exported from the Golgi towards the endosomal compartment. Overall, this study provides mechanistic insights into the alternate route used by variant of RNF13's dileucine sorting motif.