Figure 1.

Comparison of the structure of the six members of the human CELF protein family.¹²–¹⁴ CELF proteins have a similar structure comprising three conserved RR Ms, two in the N-terminus, RR M1 and RR M2 (left as shown on top bar), and a third, RR M3 (right as shown on top bar) in the C-terminus. A non conserved domain, the divergent domain, separates RR M3 from RR M2. Notable differences between the divergent domains of the CELF proteins are a serine-rich region in CELF1 (identified by primary sequence comparison), a polyglutamine stretch in CELF3,¹²,²⁶ and specific regions in the divergent domain of CELF4 which modulate its splicing activity on different pre-mRNA targets.⁷¹