PLANT PHYSIOLOGY , Vol 101, Issue 3 1005-1011, Copyright © 1993 by American Society of Plant Biologists
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CELL BIOLOGY AND SIGNAL TRANSDUCTION |
The Major Nucleoside Triphosphatase in Pea (Pisum sativum L.) Nuclei and in Rat Liver Nuclei Share Common Epitopes Also Present in Nuclear Lamins
C. G. Tong, M. Dauwalder, G. A. Clawson, C. L. Hatem and S. J. Roux
Department of Botany, The University of Texas at Austin, Austin, Texas 78713 (C.-G.T., M.D., S.J.R.)
The major nucleoside triphosphatase (NTPase) activities in mammalian and
pea (Pisum sativum L.) nuclei are associated with enzymes that are very
similar both biochemically and immunochemically. The major NTPase from rat
liver nuclei appears to be a 46-kD enzyme that represents the N-terminal
portion of lamins A and C, two lamina proteins that apparently arise from
the same gene by alternate splicing. Monoclonal antibody (MAb) G2, raised
to human lamin C, both immunoprecipitates the major (47 kD) NTPase in pea
nuclei and recognizes it in western blot analyses. A polyclonal antibody
preparation raised to the 47-kD pea NTPase (pc480) reacts with the same
lamin bands that are recognized by MAb G2 in mammalian nuclei. The pc480
antibodies also bind to the same lamin-like bands in pea nuclear
envelope-matrix preparations that are recognized by G2 and three other MAbs
known to bind to mammalian lamins. In immunofluorescence assays, pc480 and
anti-lamin antibodies stain both cytoplasmic and nuclear antigens in plant
cells, with slightly enhanced staining along the periphery of the nuclei.
These results indicate that the pea and rat liver NTPases are structurally
similar and that, in pea nuclei as in rat liver nuclei, the major NTPase is
probably derived from a lamin precursor by proteolysis.
