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The cell type-specific expression of the major nuclear lamina polypeptides ("lamins") during development of Xenopus was studied using two monoclonal antibodies (L(0)46F7: specific for LIII, the single lamin of oocytes; PKB8: specific for LI and LII of some somatic cells). In the oocyte, LIII localizes in the nuclear polymer, but upon nuclear envelope(More)
cDNA clones for nuclear pore complex glycoprotein p62 of two distantly related species, mouse and Xenopus laevis, were isolated. Antibodies raised against recombinant murine p62 react on protein blots with p62 of both species and decorate pore complexes. Analysis of the predicted protein sequence indicates that vertebrate p62 is organized into two(More)
The nuclear lamins are major components of a proteinaceous polymer that is located at the interface of the nuclear membrane and chromatin; these lamins are solubilized and dispersed throughout the cytoplasm during mitosis. It has been postulated that these proteins, assembled into the lamina, provide an architectural framework for the organization of the(More)
Morphological data suggest an interaction of the nuclear lamina with chromatin which markedly changes during the cell cycle. To study the molecular basis of this interaction we developed a novel lamin/chromatin binding assay that quantitated the binding of soluble, radiolabeled lamins to minichromosomes assembled in Xenopus laevis oocyte nuclear extracts.(More)
The nuclear lamina of vertebrates is composed of several major polypeptides that range in mol. wt from 60 to 80 kd. In mammals, the three major lamin proteins are designated A, B and C. Two major lamins have been described in Xenopus somatic tissues; two other lamins are expressed primarily in germ cells. We have analysed a cDNA clone encoding a Xenopus(More)
Immunofluorescence microscopy shows that the monoclonal murine antibody PKB8 stains the nuclear lamina of various somatic cells from vertebrates as diverse as mammals, birds and amphibia. It also decorates the nuclear periphery of oocytes from rat and chicken but does not react with spermatocytes, spermatids and spermatozoa. Immunoblotting experiments(More)
To gain insight into the mechanisms involved in the formation of maternally stored mRNPs during Xenopus laevis development, we searched for soluble cytoplasmic proteins of the oocyte that are able to selectively bind mRNAs, using as substrate radiolabeled mRNA. In vitro mRNP assembly in solution was followed by UV-cross-linking and RNase digestion,(More)
Nuclear lamin isoforms of vertebrates can be divided into two major classes. The B-type lamins are membrane associated throughout the cell cycle, whereas A-type lamins are recovered from mitotic cell homogenates in membrane-free fractions. A feature of oogenesis in birds and mammals is the nearly exclusive presence of B-type lamins in oocyte nuclear(More)
We have recently described a monoclonal antibody (X222) which localizes at pore complexes in Xenopus oocytes and immunoblots a protein under nonreducing conditions with an apparent molecular mass of 215 kDa (Cordes, Gajewski, Stumpp, Krohne, Differentiation 58, 307-312, (1995)). Under reducing conditions, this antigen decreased from the previously reported(More)
By definition, the eukaryotic cell is characterized by a compartmentation structure that divides the intracellular space into two different regions: (a) the nucleus, which contains the genome and the structures involved in transcription and processing of transcription products; and (b) the cytoplasm, which contains the translational apparatus, the cell(More)