RNA recognition motif (RRM) found in pre-mRNA cleavage factor Im 68 kDa subunit (CFIm68 or CPSF6) and similar proteins
This subgroup corresponds to the RRM of CFIm68. Cleavage factor Im (CFIm) is a highly conserved component of the eukaryotic mRNA 3' processing machinery that functions in UGUA-mediated poly(A) site recognition, the regulation of alternative poly(A) site selection, mRNA export, and mRNA splicing. It is a complex composed of a small 25 kDa (CFIm25) subunit and a larger 59/68/72 kDa subunit. Two separate genes, CPSF6 and CPSF7, code for two isoforms of the large subunit, CFIm68 and CFIm59. The family includes CFIm68, also termed cleavage and polyadenylation specificity factor subunit 6 (CPSF6), or cleavage and polyadenylation specificity factor 68 kDa subunit (CPSF68), or protein HPBRII-4/7. CFIm68 contains an N-terminal RNA recognition motif (RRM), also termed RBD (RNA binding domain) or RNP (ribonucleoprotein domain), a central proline-rich region, and a C-terminal RS-like domain. The N-terminal RRM of CFIm68 mediates the interaction with CFIm25. It also serves to enhance RNA binding and facilitate RNA looping.