Phosphorylation of nuclear proteins

Abstract

Many nuclear proteins are phosphorylated: they range from enzymes to several structural proteins such as histones, non-histone chromosomal proteins and the nuclear lamins. The pattern of phosphorylation varies through the cell cycle. Although histone H1 is phosphorylated during interphase its phosphorylation increases sharply during mitosis. Histone H3, chromosomal protein HMG 14 and lamins A, B and C all show reversible phosphorylation during mitosis. Several nuclear kinases have been characterized, including one that increases during mitosis and phosphorylates H1 in vitro. Factors have been demonstrated in maturing amphibian oocytes and mitotic mammalian cells that induce chromosome condensation and breakdown of the nuclear membrane. The possibility that they are autocatalytic protein kinases is considered. The location of histone phosphorylation sites within the nucleosome is consistent with a role for phosphorylation in modulating chromatin folding.

Regulation of the Phosphorylation of Human Pharyngeal Cell Proteins by Group A Streptococcal Surface Dehydrogenase: Signal Transduction between Streptococci and Pharyngeal Cells

“…Protein phosphorylation in general has a significant impact on cell shape, size, and motility ( 27 ), and phosphorylation of histone proteins in particular has been shown to result in condensation of chromatin structure ( 21 – 23 , 28 – 30 ). Therefore, we investigated whether we could observe these ultrastructural changes in SDH-treated Detroit cells.…”

“…Our finding that the phosphorylation of histone H3 is the result of the interaction of streptococci/SDH with human pharyngeal cells and not other cell lines is in agreement with the tissue tropism of streptococci for these cells in the human host. Phosphorylation of nuclear core proteins including histone H3 is clearly associated with structural changes in chromatin architecture ( 28 ). Since phosphorylation of histone H3 correlates directly with a late stage of chromosome condensation in mammalian cells ( 21 – 23 , 29 , 30 ), streptococcal/SDH-mediated phosphorylation of histone H3 may alter the structure and interaction of nuclear components and influence nucleosome assembly.…”

Laminin isoforms: biological roles and effects on the intracellular distribution of nuclear proteins in intestinal epithelial cells

“…2B). However, after 7 days of culture, the total number of cells was equivalent in most of the experimental conditions, probably because Second, we performed immunostaining experiments using the phospho-histone H3 [23] antibody as a mitosis marker. The data indicated that the number of mitotic cells after 3 days of culture on plates coated with laminin-2, laminin-5 and laminin-10 was higher than on laminin-1 or BSA (Fig.…”

Intranuclear binding on nucleoplasmin

“…At this time, in what is termed the unfertilized egg, Np is present throughout the cytoplasm, and it is more highly phosphorylated than nuclearly localized oocyte Np: on average 19 phosphates per egg Np polypeptide vs. 7 phosphates per oocyte Np polypeptide [Cotten et al, 19861. This increase in Np's phosphorylation, as well as its corresponding positional shift to the acidic side of 2D SDS-PAGE gels, has been thought to occur at about the time of GVBD [Laskey, 1983;Cotten et al, 1986;Sealy et al, 19863, but asynchrony in the time course of maturation among pooled oocytes has hindered precise determination of the timing with respect to GVBD of Np's hyperphosphorylation and release to the cytoplasm.…”