U1BE3

U1BE3 is a predicted eukaryotic protein that is thought to participate in RNA splicing by interacting with the U1 small nuclear ribonucleoprotein (snRNP). Based on sequence analyses, U1BE3 is a relatively small, soluble protein of approximately 30–34 kDa, containing an RNA recognition motif (RRM) near the N-terminus and a glycine-rich C-terminal region. The protein is predicted to be predominantly nuclear and localizes to spliceosomal substructures such as nuclear speckles in various cell types.

U1BE3 is conserved across several vertebrate lineages, with clear orthologs in mammals, birds, and fish, indicating an evolutionarily conserved role in RNA metabolism. Functional data are primarily inferential from domain structure and interaction studies. U1BE3 is proposed to contribute to the recruitment or stabilization of U1 snRNP at 5' splice sites, thereby influencing exon inclusion during alternative splicing. It is thought to act as an adaptor, bridging U1 snRNP components with other splicing regulators. The protein has been reported to interact with core U1 snRNP proteins as well as splicing factors; however, the precise molecular mechanism remains under investigation.

In humans, there are no established disease associations directly linked to U1BE3 variants, and population-level linkages have not been reported in major disease catalogs. Ongoing research aims to clarify its physiological roles and potential tissue-specific functions. See also U1 snRNP, pre-mRNA splicing, and RNA recognition motif.