Proteome-wide C-degron activity profiling connects conditional regulation of the CTLH E3 ligase complex to ribosome biogenesis
Year: 2026
Type: preprint
Abstract: ABSTRACT Many E3 ubiquitin ligases recognize cognate degron motifs located at protein termini, but the paucity of bona fide substrates of N-degron and C-degron pathways hampers our understanding of their physiological significance. Here, by devising an expression screening approach to assess the effect of C-terminal “capping” on the stability of thousands of human proteins, we systematically identify a suite of full-length substrates harboring C-terminal degrons. Interrogating one leading candidate, ZMYND19, we characterize a C-degron pathway governed by the Muskelin substrate adaptor of the CTLH E3 ligase complex. Cell-to-cell variability in ZMYND19 stability uncovered conditional regulation, with CTLH-mediated degradation impaired by TNF-α stimulation but enhanced by mTOR inhibition. Parallel genetic and proteomic screens identified two poorly characterized proteins, AAMP and AEN, as additional substrates of the CTLH Muskelin C-degron pathway, leading us to define an essential role for AAMP in ribosome maturation through chaperone activity towards ribosomal protein uL16. Altogether, these data define a C-degron pathway through which the Muskelin substrate adaptor connects conditional regulation of the CTLH E3 ligase complex to control of ribosome biogenesis.
Language: English
Subfield: Molecular Biology
Domain: Life Sciences
Open Access status: green
OpenAlex ID: W7124308991