RNA recognition motif 2 (RRM2) found in heterogeneous nuclear ribonucleoprotein H3 (hnRNP H3) and similar proteins
This subgroup corresponds to the RRM2 of hnRNP H3 (also termed hnRNP 2H9), a nuclear RNA binding protein that belongs to the hnRNP H protein family that also includes hnRNP H (also termed mcs94-1), hnRNP H2 (also termed FTP-3 or hnRNP H') and hnRNP F. This family is involved in mRNA processing and exhibit extensive sequence homology. Currently, little is known about the functions of hnRNP H3 except for its role in the splicing arrest induced by heat shock. In addition, the typical hnRNP H proteins contain contain three RNA recognition motifs (RRMs), also termed RBDs (RNA binding domains) or RNPs (ribonucleoprotein domains), except for hnRNP H3, in which the RRM1 is absent. RRM1 and RRM2 are responsible for the binding to the RNA at DGGGD motifs, and play an important role in efficiently silencing the exon. Members in this family can regulate the alternative splicing of the fibroblast growth factor receptor 2 (FGFR2) transcripts, and function as silencers of FGFR2 exon IIIc through an interaction with the exonic GGG motifs. The lack of RRM1 could account for the reduced silencing activity within hnRNP H3. In addition, like other hnRNP H protein family members, hnRNP H3 has an extensive glycine-rich region near the C-terminus, which may allow it to homo- or heterodimerize.