RNA recognition motif 1 (RRM1) found in heterogeneous nuclear ribonucleoprotein L (hnRNP-L) and similar proteins
This subfamily corresponds to the RRM3 of heterogeneous nuclear ribonucleoprotein L (hnRNP-L), heterogeneous nuclear ribonucleoprotein L-like (hnRNP-LL), and similar proteins. hnRNP-L is a higher eukaryotic specific subunit of human KMT3a (also known as HYPB or hSet2) complex required for histone H3 Lys-36 trimethylation activity. It plays both, nuclear and cytoplasmic, roles in mRNA export of intronless genes, IRES-mediated translation, mRNA stability, and splicing. hnRNP-LL plays a critical and unique role in the signal-induced regulation of CD45 and acts as a global regulator of alternative splicing in activated T cells. It is closely related in domain structure and sequence to hnRNP-L, which contains three RNA-recognition motifs (RRMs), also known as RBD (RNA binding domain) or RNP (ribonucleoprotein domain). The family also includes polypyrimidine tract binding protein homolog 3 (PTBPH3) found in plant. Although its biological roles remain unclear, PTBPH3 shows significant sequence similarity to polypyrimidine tract binding protein (PTB) that is an important negative regulator of alternative splicing in mammalian cells and also functions at several other aspects of mRNA metabolism, including mRNA localization, stabilization, polyadenylation, and translation. Like PTB, PTBPH3 contains four RRMs.
Lu S et al.(2020). "CDD/SPARCLE: the conserved domain database in 2020.",