FunctionMediates pre-mRNA alternative splicing regulation. Acts either as activator or repressor of splicing on specific pre-mRNA targets. Inhibits cardiac troponin-T (TNNT2) pre-mRNA exon inclusion but induces insulin receptor (IR) pre-mRNA exon inclusion in muscle. Antagonizes the alternative splicing activity pattern of CELF proteins. May play a role in myotonic dystrophy pathophysiology (DM). Could inhibit terminal muscle differentiation, acting at approximately the time of myogenin induction.
Tissue specificityHighly expressed in the placenta.
Sequence similaritiesBelongs to the muscleblind family. Contains 4 C3H1-type zinc fingers.
Cellular localizationNucleus. Cytoplasm. Greater concentration in the nucleus. In both DM1 and DM2 patients, colocalizes with nuclear foci of retained expanded-repeat transcripts.