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XB-ART-22038
J Cell Biol November 1, 1993; 123 (3): 501-12.

Membrane-associated lamins in Xenopus egg extracts: identification of two vesicle populations.

Lourim D , Krohne G .


Abstract
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 envelopes. In contrast, oocytes and early cleavage embryos of the amphibian Xenopus laevis are believed to contain a single lamin isoform, lamin LIII, which after nuclear envelope breakdown during meiotic maturation is reported to be completely soluble. Consequently, we have reexamined the lamin complement of Xenopus oocyte nuclear envelopes, egg extracts, and early embryos. An mAb (X223) specific for the homologous B-type lamins B2 of mouse and LII of Xenopus somatic cells (Höger, T., K. Zatloukal, I. Waizenegger, and G. Krohne. 1990. Chromosoma. 99:379-390) recognized a Xenopus oocyte nuclear envelope protein biochemically distinct from lamin LIII and very similar or identical to somatic cell lamin LII. Oocyte lamin LII was detectable in nuclear envelopes of early cleavage embryos. Immunoblotting of fractionated egg extracts revealed that approximately 20-23% of lamin LII and 5-7% of lamin LIII were membrane associated. EM immunolocalization demonstrated that membrane-bound lamins LII and LIII are associated with separate vesicle populations. These findings are relevant to the interpretation of nuclear reconstitution experiments using Xenopus egg extracts.

PubMed ID: 8227121
PMC ID: PMC2200128
Article link: J Cell Biol

Genes referenced: actl6a herpud1 lmnb2 lmnb3 myh3 prkg1
Antibodies: Lmnb1 Ab1 Lmnb2 Ab1 Lmnb2 Ab4 Lmnb2/3 Ab3 Lmnb2/3 Ab5 Lmnb3 Ab4


Article Images: [+] show captions
References [+] :
Bailer, Characterization of A 54-kD protein of the inner nuclear membrane: evidence for cell cycle-dependent interaction with the nuclear lamina. 1991, Pubmed


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