Mechanism for the selection of nuclear polypeptides in Xenopus oocytes: II. Two-dimensional gel analysis

Carl M. Feldherr, Joseph A. Ogburn

Research output: Contribution to journalArticlepeer-review

39 Scopus citations


The role of the nuclear envelope in controlling intracellular protein exchanges was investigated in vivo, by determining the effect of altering nuclear permeability on (a) the protein composition of the nucleoplasm and (b) the nuclear uptake rates of specific endogenous proteins. The nuclear envelopes were disrupted by puncturing oocytes in the region of the germinal vesicle by use of glass needles. Nuclear proteins were analyzed in punctured and control cells by two-dimensional gel electrophoresis, fluorography, and double-labeling techniques. Over 300 nuclear polypeptides were identified in the fluorographs. Of this number, only ~10-15 were found to vary between punctured and control nuclei ; furthermore, different polypeptides varied in each experiment. These qualitative studies indicate that specific binding within the nucleoplasm, and not selection by the envelope, is the main factor in maintaining the protein composition of the nucleus. The nuclear uptake rates of five individual polypeptides, ranging in molecular weight from 43,000 to 100,000, were analyzed by use of doublelabeling procedures. Only one of the polypeptides (actin) entered the nuclei more rapidly after disruption of the envelope. That the nuclear uptake of certain endogenous proteins is unaffected by puncturing demonstrates that passage across the envelope is not a rate-limiting step in the nucleocytoplasmic exchange of these molecules.

Original languageEnglish (US)
Pages (from-to)589-593
Number of pages5
JournalJournal of Cell Biology
Issue number3
StatePublished - Dec 1 1980
Externally publishedYes

ASJC Scopus subject areas

  • Cell Biology


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