RNA recognition motif 1 (RRM1) found in vertebrate paraspeckle protein 1 (PSP1)
This subgroup corresponds to the RRM1 of PSPC1, also termed paraspeckle component 1 (PSPC1), a novel nucleolar factor that accumulates within a new nucleoplasmic compartment, termed paraspeckles, and diffusely distributes in the nucleoplasm. It is ubiquitously expressed and highly conserved in vertebrates. Its cellular function remains unknown currently, however, PSPC1 forms a novel heterodimer with the nuclear protein p54nrb, also known as non-POU domain-containing octamer-binding protein (NonO), which localizes to paraspeckles in an RNA-dependent manner. PSPC1 contains two conserved RNA recognition motifs (RRMs), also termed RBDs (RNA binding domains) or RNPs (ribonucleoprotein domains), at the N-terminus.