HsaEX0043381 @ hg38

Exogenously expressed NOSTRINalpha is distributed over the cytosol and associated with subcellular membranes, whereas NOSTRINbeta (skipping of HsaEX0043381) is localized predominantly to the nucleus. Experiments in CHO cells.

This study shows that nuclear import of NOSTRINbeta (skipping of CDS exon HsaEX0043381, inducing the use of a downstream ATG) depends on two nuclear localization signals (aa 32-36: KKRK and aa 57-61: KAKKK). Each of the sequences is independently functional, but both are required to sustain nuclear localization of NOSTRINbeta. Export of NOSTRINbeta from the nucleus is facilitated by a CRM1-dependent mechanism relying on the nuclear export sequence LELEKERIQL (aa 135-145). Unlike NOSTRINbeta, the full-length variant NOSTRINalpha was conspicuously absent from the nucleus. This is most likely because of the fact that its N-terminal F-BAR domain, which is truncated in NOSTRINbeta, facilitates association with cellular membranes. NOSTRINbeta directly binds to the 5'-regulatory region of the NOSTRIN gene (bp -200 to -1), and overexpression of NOSTRINbeta strongly decreases transcription of a reporter gene under control of this DNA region.