Characterization of a second member of the sentrin family of ubiquitin-like proteins.
Sentrin is a novel ubiquitin-like protein that can be conjugated to other proteins in a manner analogous to ubiquitination. Two additional cDNA sequences that encode proteins highly homologous to sentrin have been reported to GenBankTM. It is not known whether these sentrin-like proteins could also function as protein modifiers. In this report, a second member of the sentrin family was characterized in detail. Sentrin-2 is a 95-amino acid polypeptide that is 46% identical and 66% homologous to sentrin-1. Northern blot analysis showed that the sentrin-2 message was expressed in all tissues, but was barely detectable in the liver and placenta. The ability of sentrin-2 to conjugate to other proteins was tested by expressing hemagglutinin epitope-tagged sentrin-2 in COS cells. Western blot analysis showed that sentrin-2 could be transferred to other proteins in a pattern similar to that of sentrin-1 conjugation and had similar C-terminal processing. We further showed that both sentrin-1 and sentrin-2 could covalently modify RanGAP1, a Ran GTPase-activating protein critically involved in nuclear transport. Immunocytochemical analysis showed that sentrin-2 derivatives were highly enriched in the nucleus. Taken together, our results demonstrate that sentrin-2 is another protein modifier for the sentrinization pathway.
Kamitani
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T
Department of Internal Medicine, University of Texas-Houston Health Science Center, Houston, Texas 77030, USA.
Kito
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K
Nguyen
H P
HP
Fukuda-Kamitani
T
T
Yeh
E T
ET
D000595:Amino Acid Sequence; D000818:Animals; D019556:COS Cells; D018076:DNA, Complementary; D006801:Humans; D008969:Molecular Sequence Data; D011499:Protein Processing, Post-Translational; D025842:SUMO-1 Protein; D017386:Sequence Homology, Amino Acid; D014452:Ubiquitins / Q000737:chemistry*
D018076:DNA, Complementary; D025842:SUMO-1 Protein; D014452:Ubiquitins