THE NUCLEAR MATRIX PROTEINS (MOL. MASS 38 AND 50 kDa) ARE TRANSPORTED
BY CHROMOSOMES IN MITOSIS
M. I. Murasheva, Yu. S. Chentsov
M. V. Lomonosov Moscow State University, Biology Department;
e-mail: marinak-m@mail.ru, yuchentsov@mail.ru
It was shown by immunofluorescence method that serum M68 and serum K43 from patients with autoimmune
disease stain interphase nuclei and periphery of mitotic chromosomes of pig kidney cells. Western blotting
reveals the polypeptide with mol. mass of 50 kDa in serum M68, and the polypeptide with mol. mass of
38 kDa in serum K43. In the nuclear protein matrix, the antibodies to protein with mol. mass of 38 kDa stained
only nucleolar periphery, while the antibodies to the protein with mol. mass of 50 kDa stained both the nucleolar
periphery and all the interphase nucleus. It shows that among all components of nuclear protein matrix (lamina,
internuclear network, residual nucleoli) only nucleolar periphery contains the 38 kDa protein, while the 50 kDa
protein is a part of residual nucleolar periphery and takes part in nuclear protein network formation. In the interphase
cells, both proteins were in situ localized in the nuclei, but one of them with mol. mass of 50 kDa was in
the form of small clearly outlined granules, while the other (38 kDa) was in the form of small bright granules
against the background of diffusely stained nuclei. Both proteins were also revealed as continuous ring around
nucleolar periphery. During all mitotic stages, the 50 kDa protein was seen on the chromosomal periphery as a
cover, and the 38 kDa protein formed separate fragments and granules around them. After nuclear and chromosome
decondensation induced by hypotonic treatment, both antibodies stain interphase nuclei in diffuse manner,
but in mitotic cells they stained the surface of the swollen chromosomes. The polypeptide with mol. mass of
50 kDa maintained strong connection with chromosome periphery both in norm and under condition of decondensation
induced by hypotonic treatment and at subsequent recondensation in isotonic medium. In contrast, the
protein with mol. mass of 38 kDa partially lost the contact with a chromosome during recondensation appearing
also in the form of granules in cytoplasm. The data allow to consider, that nuclear matrix proteins can be transported
as a part of peripheral chromosomal material, and that they can have connection of different stability with
chromosomal periphery as well as the main nucleolar proteins (fibrillarin, B-23, nucleolin et al.) and some
non-nucleolar components of nuclear protein matrix.
Key words: chromosome, immunochemistry, mitosis, nuclear protein matrix, nucleolus, hypotonic treatment
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