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Divergent N-terminal sequences target an inducible testis deubiquitinating enzyme to distinct subcellular structures.

Abstract : Ubiquitin-specific processing proteases (UBPs) presently form the largest enzyme family in the ubiquitin system, characterized by a core region containing conserved motifs surrounded by divergent sequences, most commonly at the N-terminal end. The functions of these divergent sequences remain unclear. We identified two isoforms of a novel testis-specific UBP, UBP-t1 and UBP-t2, which contain identical core regions but distinct N termini, thereby permitting dissection of the functions of these two regions. Both isoforms were germ cell specific and developmentally regulated. Immunocytochemistry revealed that UBP-t1 was induced in step 16 to 19 spermatids while UBP-t2 was expressed in step 18 to 19 spermatids. Immunoelectron microscopy showed that UBP-t1 was found in the nucleus while UBP-t2 was extranuclear and was found in residual bodies. For the first time, we show that the differential subcellular localization was due to the distinct N-terminal sequences. When transfected into COS-7 cells, the core region was expressed throughout the cell but the UBP-t1 and UBP-t2 isoforms were concentrated in the nucleus and the perinuclear region, respectively. Fusions of each N-terminal end with green fluorescent protein yielded the same subcellular localization as the native proteins, indicating that the N-terminal ends were sufficient for determining differential localization. Interestingly, UBP-t2 colocalized with anti-gamma-tubulin immunoreactivity, indicating that like several other components of the ubiquitin system, a deubiquitinating enzyme is associated with the centrosome. Regulated expression and alternative N termini can confer specificity of UBP function by restricting its temporal and spatial loci of action.
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Contributeur : Anne Keriel Connectez-vous pour contacter le contributeur
Soumis le : vendredi 25 janvier 2019 - 14:05:51
Dernière modification le : mardi 15 février 2022 - 07:58:01


  • HAL Id : hal-01994377, version 1
  • PUBMED : 10938131



L. Lin, Anne Keriel, C. Morales, N Bedard, Q. Zhao, et al.. Divergent N-terminal sequences target an inducible testis deubiquitinating enzyme to distinct subcellular structures.. Molecular and Cellular Biology, American Society for Microbiology, 2000, 20 (17), pp.6568-78. ⟨hal-01994377⟩



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