Nuclear speckles are subnuclear storage sites containing pre-mRNA splicing machinery. Nuclear speckle splicing regulatory protein 1 (Nsrp1), also known as NSRP70, is a nuclear speckle-related protein that mediates alternative splice site selection, targeting several pre-mRNAs []. It contains an N-terminal coiled-coil domain that is critical not only for self-oligomerization but also for splicing activity. It interacts physically with two SR (serine/arginine) proteins, SRSF1 and SRSF2, and reverses their splicing activity in terms of CD44 exon v5 as exon exclusion [].
