PRAMEF27

Model summary

A nucleocytoplasmic adaptor that assembles with a cullin-RING ubiquitin ligase to promote ubiquitination and proteasome-dependent turnover of selected targets. Its N-terminal PRAME-like module nucleates ligase assembly, while a long leucine-rich repeat scaffold confers high-specificity substrate recognition. By recruiting transcriptional regulators to a CUL2-based complex, it drives their ubiquitylation and subsequent degradation, thereby coupling targeted protein turnover to broader control of cellular pathways.

Predicted Gene Ontology terms

1. 01

   I begin with the InterPro architecture.

   The N-terminus carries IPR060378 (PRAME-like, N-terminal domain, residues 8–115), followed by an extended leucine-rich repeat scaffold defined by IPR032675 (Leucine-rich repeat domain superfamily, residues 154–413) and IPR060377 (PRAME-like, C-terminal LRR domain, residues 149–478). Two family-level envelopes, IPR026271 (PRAME family, residues 3–476) and IPR050694 (LRRC14/PRAME family, residues 3–464), span essentially the full length, indicating a conserved PRAME/LRRC14 adaptor framework. The ordered layout—an N-terminal PRAME-like module feeding into a long LRR array—creates a bipartite recognition platform: the N-terminal PRAME-like domain typically mediates initial docking to partner proteins, while the LRR solenoid provides a curved surface for high-specificity substrate capture and assembly of larger complexes.

2. 02

   This architecture causes adaptor activity rather than catalysis.

   LRR arrays are classical specificity modules in ubiquitin ligase pathways, and the PRAME family is known for assembling with cullin-RING ligases. The presence of a dedicated PRAME-like N-terminus coupled to an extensive LRR tract supports a molecular function of recruiting substrates to ubiquitin ligase machinery, matching GO:1990756 ubiquitin ligase-substrate adaptor activity. By physically bridging targets to a CUL2-based RING ligase, the protein positions substrates for ubiquitin transfer.

3. 03

   Substrate delivery to a CUL2-RING complex drives proteasome-directed turnover.

   This adaptor-driven ubiquitination feeds directly into GO:0043161 proteasome-mediated ubiquitin-dependent protein catabolic process. The LRR scaffold’s role is to concentrate and present specific targets—such as transcriptional regulators—to the E3 core for polyubiquitylation and subsequent degradation.

4. 04

   Cellular context follows from the assembly pathway.

   The explicit association with a CUL2-RING platform places the protein within GO:0031462 Cul2-RING ubiquitin ligase complex. Such assemblies operate in both cytoplasm and nucleus, consistent with shuttling adaptors that regulate nuclear transcriptional factors and cytoplasmic signaling nodes. The absence of transmembrane features and the soluble LRR architecture further support a nucleocytoplasmic adaptor that traffics with the ligase complex.

5. 05

   Mechanistically, the N-terminal PRAME-like domain likely nucleates binding to the CRL2 core (via DDB1-CUL2 or accessory factors), while the C-terminal LRR array confers substrate selectivity and avidity.

   This arrangement predicts transient interactions with CRL2 constituents and substrate transcription factors. I hypothesize that the adaptor binds DDB1 and CUL2 to assemble a functional ligase, captures specific nuclear substrates through its LRR surface, and channels them to the proteasome. Likely partners include the CRL2 core (CUL2, DDB1, RBX1), assembly cofactors (CAND1, SWAP), and candidate nuclear substrates such as transcriptional regulators whose turnover tunes gene expression and cell-state transitions.