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Updated: May 12, 2026

Analysis of Protein Import into Chloroplasts Isolated from Stressed Plants
Published on: November 1, 2016
Isolation of a protein that is essential for the first step of nuclear protein import
D Görlich1, S Prehn, R A Laskey
1Wellcome/CRC Institute, Cambridge, England.
Abstract:
We have purified a cytosolic protein from Xenopus eggs that is essential for selective protein import into the cell nucleus. The purified protein, named importin, promotes signal-dependent binding of karyophilic proteins to the nuclear envelope. We have cloned, sequenced, and expressed a corresponding cDNA. Importin shows 44% sequence identity with SRP1p, a protein associated with the yeast nuclear pore complex. Complete, signal-dependent import into HeLa nuclei can be reconstituted by combining importin purified from Xenopus eggs or expressed in E. coli with Ran/TC4. Evidence for additional stimulatory factors is provided.
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