DisnRNP

DisnRNP, short for disordered-domain ribonucleoprotein particle, is a proposed class of nuclear ribonucleoproteins identified in studies of pre-mRNA processing and spliceosome dynamics. Unlike canonical snRNPs, disnRNPs are described as containing extensive intrinsically disordered regions in many protein components and potentially carrying a noncanonical mix of RNA elements alongside the conventional small nuclear RNA core. The term arose from proteomic and crosslinking approaches that repeatedly found splicing-associated complexes dominated by disorder-prone proteins and flexible RNA content, suggesting a more dynamic, assembly-prone contributor to RNA processing.

Composition and properties: disnRNPs appear to assemble from core snRNPs and additional factors, with proteins that often feature low-complexity domains and RNA-binding motifs. Their RNA content can be heterogeneous, including canonical snRNA remnants and novel RNA fragments. The particles are highly dynamic, with assembly influenced by cellular conditions, post-translational modifications, and molecular crowding. Functionally, they are proposed to modulate spliceosome assembly, influence alternative splicing decisions, and participate in RNA quality control by acting as scaffolds or regulators of transition steps.

Status and significance: disnRNPs remain a subject of debate and are not yet universally accepted as stable entities. Evidence is preliminary and sometimes contradictory, requiring further replication. If validated, disnRNPs could broaden understanding of splicing diversity and offer new angles on diseases linked to splicing defects. Ongoing work employs affinity purification, crosslinking, and RNA profiling to resolve their composition and roles. Further reading on noncanonical snRNPs and RNA processing is available in reviews of spliceosome diversity.