We report here that a 62 kDa calmodulin-binding protein (p62), recently identified in the nucleus of rat hepatocytes, neurons and glial cells, consists of four polypeptides showing pI values between 5.9 and 6.1. By using a DNA-binding overlay assay we found that the two most basic of the p62 polypeptides bind both single- and double-stranded DNA. The intranuclear distribution of calmodulin and p62 was analysed in hepatocytes and astrocyte precursor cells, and in proliferating and differentiated astrocytes in primary cultures by immunogold-labeling methods. In non-dividing cells nuclear calmodulin was mostly localized in heterochromatin although it was also present in euchromatin and nucleoli. A similar pattern was observed for p62, with the difference that it was not located in nucleoli. p62/calmodulin complexes, mainly located over heterochromatin domains were also observed in interphasic cells. These complexes remained associated with the nuclear matrix after in situ sequential extraction with nucleases and high-salt containing buffers. In dividing cells, both calmodulin and p62 were found distributed over all the mitotic chromosomes but the p62/calmodulin aggregates were disrupted. These results suggest a role for calmodulin and p62 in the condensation of the chromatin.
Nuclear calmodulin/62 kDa calmodulin-binding protein complexes in interphasic and mitotic cells
- Views Icon Views
- PDF LinkPDF
- Share Icon Share
- Search Site
M. Portoles, M. Faura, J. Renau-Piqueras, F.J. Iborra, R. Saez, C. Guerri, J. Serratosa, E. Rius, O. Bachs; Nuclear calmodulin/62 kDa calmodulin-binding protein complexes in interphasic and mitotic cells. J Cell Sci 1 December 1994; 107 (12): 3601–3614. doi: https://doi.org/10.1242/jcs.107.12.3601
Download citation file: