Editors' ChoiceGrowth Factor Receptors

Ubiquitin-Mediated Receptor Internalization

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Science's STKE  25 Jan 2000:
Vol. 2000, Issue 16, pp. tw3
DOI: 10.1126/stke.2000.16.tw3

Cells can attenuate signals propagated through activated plasma membrane receptors by removing the receptors from the cell surface. Signal downmodulation can occur through internalization of activated receptors in which case the receptors must possess internalization motifs in their cytoplasmic tails. Di-leucine and tyrosine based motifs in the cytoplasmic tails of receptors have been identified that function as tags for internalization. Ubiquitination of plasma membrane receptors also tags proteins for internalization and subsequent endocytic pathway degradation. But it has not been established whether the process of ubiquitination causes the unmasking of a cryptic internalization motif or whether the presence of ubiquitin (Ub) itself is sufficient for internalization. After binding its cognate ligand, the yeast alpha factor receptor, Ste2p, is quickly ubiquitinated and internalized. By generating a chimeric Ste2p molecule whose the cytoplasmic tail is replaced by Ub, Shih et al. demonstrate that ubiquitination alone can mediate activation-dependent internalization of the receptor.

Shih, S.C., Sloper-Mould, K.E., and Hicke, L. (2000) Monoubiquitin carries a novel internalization signal that is appended to activated receptors. EMBO J. 19: 187-198. [Abstract] [Full Text]

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