omega speckle

GO:0035062 · Ribonucleoprotein · Other · Proposed

A nucleoplasmic speckle distributed in the interchromatin space of cells in close proximity to chromatin. Omega speckles are distinct from interchromatin granules and contain heterogeneous nuclear RNA-binding proteins (hnRNPs). [GO:0035062]

Part of: nuclear lumen (GO:0031981)

UniProt location names: UniProt Consortium, CC BY 4.0. Reference label and route sources.

Components

Component	Type	Part of / acts on	Grounding	Genes	Stoichiometry	Essential	Role
hsr-omega-n lncRNA	Rna	part of	Reviewed label only (reviewed name; no accession asserted)	hsr-omega		ESSENTIAL	Noncoding nuclear RNA that organizes and maintains hnRNP-containing omega speckles in the Drosophila nucleoplasm. `DOI:10.1242/jcs.113.19.3485` Prasanth et al. 2000 localized hsr-omega-n transcripts to omega speckles and found that the hnRNP speckled pattern was lost in hsr-omega nullosomics.
Drosophila hnRNP cohort	Protein	part of	Reviewed label only (reviewed name; no accession asserted)	Hrb87F, Hrp40, Hrb57A, S5		UNKNOWN	Heterogeneous nuclear RNA-binding proteins that colocalize with hsr-omega transcripts in omega speckles and physically associate with hsr-omega RNA. `DOI:10.1242/jcs.113.19.3485` Prasanth et al. 2000 colocalized HRB87F, Hrp40, Hrb57A and S5 hnRNPs with omega speckles and detected physical association between hnRNPs and hsr-omega transcripts.

Taxonomic distribution

NCBITaxon:7227 Drosophila melanogaster — VARIABLE: Omega speckles were discovered in Drosophila melanogaster larval and adult cell types as hsr-omega-n RNA- and hnRNP-containing nuclear speckles whose number varies by cell type and heat-shock state. [DOI:10.1242/jcs.113.19.3485]

Canonical examples

NCBITaxon:7227 Drosophila melanogaster — Drosophila melanogaster cells were used to define omega speckles as hsr-omega nuclear-transcript foci that colocalize with hnRNPs and remain distinct from SR-protein interchromatin granules. [DOI:10.1242/jcs.113.19.3485]

Functions

hnRNP trafficking and availability regulation — Drosophila omega speckles organize hsr-omega-n noncoding RNA and hnRNP proteins in nuclear foci that regulate the trafficking and availability of hnRNPs and related RNA-binding proteins.
- DOI:10.1242/jcs.113.19.3485 Prasanth et al. 2000 concluded from hsr-omega localization, hnRNP colocalization and hsr-omega-nullosomic disruption that omega speckles organize hnRNP trafficking and availability.

Mechanism graphs

hsr-omega RNA organizes hnRNP omega speckles (ASSEMBLY)

The Drosophila hsr-omega-n nuclear noncoding transcript localizes in omega speckles, colocalizes and physically associates with hnRNP proteins in the same foci, and is required for their speckled nuclear distribution.

Subject	Predicate	Object	Evidence
hsr-omega-n lncRNA	localizes to	omega speckle	`DOI:10.1242/jcs.113.19.3485` Prasanth et al. 2000 used RNA in situ hybridization to localize hsr-omega-n transcripts to omega speckles.
Drosophila hnRNP cohort	colocalizes with	hsr-omega-n lncRNA	`DOI:10.1242/jcs.113.19.3485` Prasanth et al. 2000 found absolute colocalization of tested hnRNPs with omega speckles.
omega speckle	is distinct from	interchromatin granule	`GO:0035062` GO:0035062 defines omega speckles as distinct from interchromatin granules. `DOI:10.1242/jcs.113.19.3485` Prasanth et al. 2000 reported that SC35 and SRp55 SR-protein nuclear speckles did not colocalize with omega speckles.
hsr-omega-n lncRNA	organizes	hnRNP trafficking and availability regulation	`DOI:10.1242/jcs.113.19.3485` Prasanth et al. 2000 found that hnRNP speckling was disrupted in hsr-omega nullosomics and connected omega speckles to hnRNP trafficking and availability.

Discussions

CURATION_TODO (OPEN): Resolve exact hsr-omega-n RNA, Drosophila hnRNP and heat-shock remodeling boundaries for omega speckles. This first GO:0035062 record captures the defining hsr-omega-n RNA and a tested hnRNP cohort while leaving exact noncoding transcript isoforms, source-neutral hnRNP family groundings, candidate additional RNA-binding proteins and the heat-shock-driven coalescence pathway to a later pass.

Evidence

GO:0035062 Gene Ontology cellular-component term for omega speckle.
GO:0016607 Gene Ontology cellular-component parent term for nuclear speck.
GO:0140168 Gene Ontology cellular-component ancestor term for nuclear ribonucleoprotein granule.
GO:0031981 Gene Ontology cellular-component term for the nuclear lumen; omega speckles are nucleoplasmic speckles.
DOI:10.1242/jcs.113.19.3485 Prasanth, Rajendra, Lal and Lakhotia 2000, Omega speckles - a novel class of nuclear speckles containing hnRNPs associated with noncoding hsr-omega RNA in Drosophila, Journal of Cell Science.

Curation history

2026-09-28T05:51:58Z codex · CREATED_RECORD — Scaffolded by scripts/new_record.py
2026-09-28T05:52:48Z codex · EXPANDED_RECORD — Added nuclear-speck and nuclear-RNP-granule parentage, nuclear-lumen parthood, hsr-omega-n RNA and Drosophila hnRNP components, Drosophila melanogaster scope, hnRNP trafficking evidence, a nonmechanistic hsr-omega omega-speckle organization graph and a component-boundary TODO.
2026-09-28T06:08:56Z codex · RESOLVED_REVIEW — Resolved #1706 by rewording the omega speckle graph description to state hsr-omega-n/hnRNP colocalization, physical association and dependence without claiming active hnRNP recruitment.

Source: data/structures/ribonucleoprotein/omega_speckle.yaml