Serine/Arginine Repetitive Matrix Protein 2 (SRRM2)

The deduced 2,752-amino acid protein has multiple R, S, and P residues, numerous phosphorylation sites, and a predicted molecular mass of 300 kD, suggesting that it may be the full-length protein. Immunoblot analysis detected GST fusion proteins of greater than 300 kD in human and rat cells. Northern blot analysis revealed expression of a 9.0- to 10.0-kb SRL300 transcript in all tissues and cell lines tested.Like SRM160, the deduced 2,296-amino acid SRM300 protein is rich in serine (S), arginine (R), and proline (P), has numerous SR dipeptides and 2 long polyserine domains, and lacks an RNA recognition domain. Reconstitution of SRM160/SRM300-depleted splicing reactions with recombinant SRM160 restored splicing activity, suggesting that SRM160 is the more important component of the complex.