FIG 11.

A proposed model of the role of RBM45 in B19V pre-mRNA processing. RBM45 is a scaffold protein that functions to bring the 5′ and 3′ splice sites into close proximity. The B19V pre-mRNA is depicted, with cis elements of D2 donor, A2-1/2 acceptors, and exon splicing enhancers (ESE) and intron splicing enhancers (ISE) indicated, together with interacted splicing factors, U1, U2, RBM45, and potential mediator proteins (M). Spliced mRNAs that encode VP1, VP2, and 11-kDa protein are diagrammed, with the dashed lines indicating introns. U1 and U2 represent U1-small nuclear ribonucleoprotein (snRNP) and U2-snRNP complexes, and M represents protein mediators associated with U1-snRNP and U2-snRNP complexes. Dotted circles represent ISE-binding proteins (ISE2/3-BPs). Question marks indicate unknown factors. The approximate size of each mRNA is indicated, and the cap probe for Northern blotting is diagrammed.