- Title
- The α-importome of mammalian germ cell maturation provides novel insights for importin biology
- Creator
- Arjomand, Arash; Baker, Mark A.; Li, Chen; Buckle, Ashley M.; Jans, David A.; Loveland, Kate L.; Miyamoto, Yoichi
- Relation
- ARC.DP0878102
- Relation
- The FASEB Journal Vol. 28, Issue 8, p. 3480-3493
- Publisher Link
- http://dx.doi.org/10.1096/fj.13-244913
- Publisher
- Federation of American Societies for Experimental Biology
- Resource Type
- journal article
- Date
- 2014
- Description
- Importin α proteins function as adaptors to connect a cargo protein and importin ß1 in the classical nuclear import pathway. Here we measure for the first time the stoichiometry of importins α2, α3, α4, and ß1 in primary cells corresponding to 2 successive stages of rat spermatogenesis: meiotic spermatocytes and haploid round spermatids. Importin α2 levels were more than 2-fold higher in spermatocytes than in spermatids, while importins α4 and ß1 levels did not differ significantly. We performed a comprehensive proteomics analysis to identify binding proteins in spermatocytes and spermatids using recombinant importin α2 and α4 proteins. Among the 100 candidate partners, 42 contained a strong classical nuclear localization signal (cNLS; score of>6 by cNLS Mapper), while 8 nuclear proteins lacked any cNLS. In addition, we developed a new strategy to predict which cargoes bind to importin a through the conserved C-terminal acidic domain (ARM repeats 9-10), and provided functional validation of a predicted importin α C-terminal binding segment in Senataxin and Smarca4. Evaluation of this set of candidate binding partners from spermatogenic cells using several bioinformatics approaches provides new evidence that individual importin αs may serve unique and nonredundant roles in mediating cellular differentiation.
- Subject
- nuclear transport; spermatogenesis; mass spectrometry; nuclear localization signal
- Identifier
- http://hdl.handle.net/1959.13/1304003
- Identifier
- uon:20774
- Identifier
- ISSN:1530-6860
- Language
- eng
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