Identification of importin ? 7 specific transport cargoes using a proteomic screening approach.

ABSTRACT: The importin ?:? complex is responsible for the nuclear import of proteins bearing classical nuclear localization signals. In mammals, several importin ? subtypes are known to exist that are suggested to have individual functions. Importin ? 7 was shown to play a crucial role in early embryonic development in mice. Embryos from importin ? 7-depleted females stop at the two-cell stage and show disturbed zygotic genome activation. As there is evidence that individual importin ? subtypes possess cargo specificities, we hypothesized that importin ? 7 binds a unique set of intracellular proteins. With the use of a collection of in vitro and in vivo binding assays, importin ? 7 interaction partners were identified that differed from proteins found to bind to importin ? 2 and 3. One of the proteins preferentially binding importin ? 7 was the maternal effect protein Brg1. However, Brg1 was localized in oocyte nuclei in importin ? 7-deficient embryos, albeit in reduced amounts, suggesting additional modes of nuclear translocation of this factor. An additional SILAC-based screening approach identified Ash2l, Chd3, Mcm3, and Smarcc1, whose nuclear import seems to be disturbed in importin ? 7-deficient fibroblasts.

SUBMITTER: Hugel S 

PROVIDER: S-EPMC4014285 | biostudies-literature | 2014 May

REPOSITORIES: biostudies-literature