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The inner nuclear membrane protein Sun1 mediates the anchorage of Nesprin-2 to the nuclear envelope

Padmakumar, V.C.; Libotte, T.; Lu, W.S.; Zaim, H.; Abraham, S.; Noegel, A.A.; Gotzmann, J.; Foisner, R.; Karakesisoglou, I.


V.C. Padmakumar

T. Libotte

W.S. Lu

H. Zaim

S. Abraham

A.A. Noegel

J. Gotzmann

R. Foisner


Nesprins form a novel class of nuclear envelope-anchored spectrin-repeat proteins. We show that a direct association of their highly conserved C-terminal luminal domain with the inner nuclear membrane protein Sun1 mediates their nuclear envelope localisation. In Nesprin-1 and Nesprin-2 the conserved C-terminal amino acids PPPX are essential for the interaction with a C-terminal region in Sun1. In fact, Sun1 is required for the proper nuclear envelope localisation of Nesprin-2 as shown using dominant-negative mutants and by knockdown of Sun1 expression. Sun1 itself does not require functional A-type lamins for its localisation at the inner nuclear membrane in mammalian cells. Our findings propose a conserved nuclear anchorage mechanism between Caenorhabditis elegans and mammals and suggest a model in which Sun1 serves as a `structural bridge' connecting the nuclear interior with the actin cytoskeleton.


Padmakumar, V., Libotte, T., Lu, W., Zaim, H., Abraham, S., Noegel, A., …Karakesisoglou, I. (2005). The inner nuclear membrane protein Sun1 mediates the anchorage of Nesprin-2 to the nuclear envelope. Journal of Cell Science, 118(15), 3419-3430.

Journal Article Type Article
Publication Date Aug 1, 2005
Deposit Date Jan 17, 2008
Journal Journal of Cell Science
Print ISSN 0021-9533
Electronic ISSN 1477-9137
Publisher The Company of Biologists
Peer Reviewed Peer Reviewed
Volume 118
Issue 15
Pages 3419-3430
Keywords Emerin, Enaptin, Lamin A/C, NUANCE, SUN domain, Syne.