Integral membrane proteins of the nuclear envelope interact with lamins and chromosomes, and binding is modulated by mitotic phosphorylation.
Lamina-associated polypeptides (LAPs) 1A, 1B, 1C, and 2 are integral membrane proteins of the nuclear envelope associated with the nuclear lamina. Using in vitro assays, we show that LAPs 1A and 1B specifically bind to both lamins A and C and lamin B1, while LAP 2 associates only with lamin B1. LAP 2 also binds to mitotic chromosomes. The LAPs are phosphorylated during mitosis, and phosphorylation of LAP 2 by mitotic cytosol inhibits its binding to both lamin B1 and chromosomes. During late anaphase, LAP 2 associates with chromosomes prior to assembly of most lamins. Together, these data suggest that LAP 2 may have a key role in initial events of nuclear envelope reassembly, and that both LAP 2 and LAP 1 may be involved in attaching lamins to the nuclear envelope.
Foisner
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R
Department of Cell Biology, Scripps Research Institute, La Jolla, California 92037.
Gerace
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L
D000818:Animals; D001665:Binding Sites; D016466:CHO Cells; D002875:Chromosomes; D006224:Cricetinae; D034921:Lamin Type B; D034882:Lamins; D008099:Liver / Q000378:metabolism; D008565:Membrane Proteins / Q000032:analysis / Q000378:metabolism*; D008861:Microsomes / Q000378:metabolism; D008938:Mitosis; D009685:Nuclear Envelope / Q000378:metabolism*; D009687:Nuclear Proteins / Q000378:metabolism*; D010766:Phosphorylation; D051381:Rats
D034921:Lamin Type B; D034882:Lamins; D008565:Membrane Proteins; D009687:Nuclear Proteins