SRp55

SRp55 is a serine/arginine-rich (SR) splicing factor that belongs to the SR protein family. Members of this family are involved in the regulation of pre-mRNA splicing, in particular alternative splicing. SRp55 proteins typically migrate around 55 kilodaltons and contain one or more RNA recognition motifs (RRMs) for binding RNA, together with an arginine-serine-rich (RS) domain that mediates protein interactions and regulation by phosphorylation.

Function: SRp55 participates in recognizing exonic splicing enhancers and modulating splice site selection, promoting exon inclusion in some transcripts and exon skipping in others depending on context and interacting partners.

Structure and regulation: The RS domain is a major regulatory module; its phosphorylation state, controlled by SR protein kinases such as SRPK and CLK family kinases, influences localization and splicing activity.

SRp55 typically resides in the nucleus but can shuttle to the cytoplasm under certain conditions.

Interactions and localization: It interacts with core spliceosome components and other SR proteins; localization and activity are influenced by cellular signals and developmental stage.

Clinical and research notes: Misregulation of SRp55 has been reported in studies of cancer and other diseases, reflecting a broader role for SR proteins in gene expression regulation.

Because of its central role in splicing, SRp55 is a common subject of studies on RNA processing and post-transcriptional control.