Serine/Arginine Repetitive Matrix Protein 1 (SRRM1)

SRM160 also has multiple putative phosphorylation sites and SH3-binding motifs but no RNA-recognition domains. Northern blot analysis revealed expression of a ubiquitous, variably expressed 3.8-kb transcript and a more restricted 6.0-kb transcript. Immunoblot analysis showed that the recombinant protein was expressed as a 160-kD protein in nuclear extract and that it could be reduced to a 120-kD protein by phosphatase treatment. Confocal microscopy demonstrated expression of SRM160 in nuclear speckles. Immunoprecipitation analysis detected interaction of SRM160 with SRM300, a nuclear matrix antigen, and 2 other SR proteins, SRp40 and SRp75 . EMSA analysis indicated that SRM160/SRM300 associates with pre-mRNA and promotes splicing through interactions with SR family proteins.