Protein delivery to restricted plasma membrane domains is exquisitely regulated at different stages of the cell trafficking machinery. Traffic control involves the recognition of export/retention/retrieval signals in the endoplasmic reticulum (ER)/Golgi complex that will determine protein fate. A splice variant (SV), SV1, of the voltage- and Ca2+-activated K+ channel α-subunit accumulates the channel in the ER, preventing its surface expression. We show that SV1 insert contains a nonbasic, hydrophobic retention/retrieval motif, CVLF, that does not interfere with proper folding and tetramerization of SV1. Localization of proteins in the ER by CVLF is independent of its position; originally, on the first internal loop, SV1 insert or CVLF perform equally well if placed at the middle or end of the α-subunit intracellular carboxyl terminus. Also, CVLF is able to restrict the traffic of an independently expressed transmembrane protein, β1-subunit. CVLF is present in proteins across species and in lower organisms. Thus, CVLF may have evolved to serve as a regulator of cellular traffic.
Zarei, M. M., Eghbali, M., Alioua, A., Song, M., Knaus, H.-G., Stefani, E., & Toro, L. (2004). An endoplasmic reticulum trafficking signal prevents surface expression of a voltage- and Ca2+-activated K+ channel splice variant. Proceedings of the National Academy of Sciences, 101(27), 10072–10077. https://doi.org/10.1073/pnas.0302919101
Proceedings of the National Academy of Sciences