Two conserved serines in the nuclear localization signal flanking region are involved in the nuclear targeting of human lamin A.
Eur J Cell Biol 1995;
68:133-42. [PMID:
8575460]
[Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
The nuclear lamins are karyophilic proteins located at the nucleoplasmic surface of the inner nuclear membrane. We have constructed mutants immediately N-terminal to the nuclear localization signal of human lamin A to identify sites regulating the nuclear transport of the protein. Using an in vitro transport assay, we determined the short-term kinetics of nucleocytoplasmic transport of wild type and mutant proteins. The double mutation of two putative protein kinase C sites (serine 403/404-->alanine) reduced the rate of nuclear import for the mutant protein. Inhibition of phosphorylation in wild type lamin A by the specific protein kinase C inhibitors 1-(5-isoquinolinesulfonyl)-2-methylpiperazine (H7) and staurosporine or treatment with acid or alkaline phosphatase decreased the nuclear import of the protein. We suggest that transport of human lamin A into the nucleus is regulated by phosphorylations of protein kinase C sites in the sequence N-terminal to the nuclear localization signal.
Collapse