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XB-ART-27513
J Cell Biol May 1, 1988; 106 (5): 1435-44.
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The function of the nuclear envelope in nuclear protein accumulation.

Zimmer FJ , Dreyer C , Hausen P .


Abstract
The mechanism by which proteins accumulate in the cell nucleus is not yet known. Two alternative mechanisms are discussed here: (a) selective unidirectional entry of karyophilic proteins through the nuclear pores, and (b) free diffusion of all proteins through the nuclear pores and specific binding of nuclear proteins to nondiffusible components of the nucleoplasm. We present experiments designed to distinguish between these alternatives. After mechanical injury of the Xenopus oocyte nuclear envelope, nuclear proteins were detected in the cytoplasm by immunohistochemical methods. In a second approach, nuclei from X. borealis oocytes were isolated under oil, the nuclear envelopes were removed, and the pure nucleoplasm was injected into the vegetal pole of X. laevis oocytes. With immunohistochemical methods, it was found that each of five nuclear proteins rapidly diffuses out of the injected nucleoplasm into the surrounding cytoplasm. The subsequent transport and accumulation in the intact host nucleus could be shown for the nuclear protein N1 with the aid of a species-specific mAb that reacts only with X. borealis N1. Purified and iodinated nucleoplasmin was injected into the cytoplasm of Xenopus oocytes and its uptake into the nucleus was studied by biochemical methods.

PubMed ID: 3372586
PMC ID: PMC2115041
Article link:


Species referenced: Xenopus laevis
Genes referenced: gnl3 npm1 tbx2
Antibodies: Germinal Vesicle Ab4


Article Images: [+] show captions
References [+] :
Bonner, Protein migration into nuclei. I. Frog oocyte nuclei in vivo accumulate microinjected histones, allow entry to small proteins, and exclude large proteins. 1975, Pubmed, Xenbase