Using a monoclonal antibody we have identified and cDNA-cloned a novel type of protein localized, by light and electron microscopy, to the plaque associated with the cytoplasmic face of the tight junction-containing zone (zonula occludens) of polar epithelial cells and of Sertoli cells of testis, but absent from the junctions of vascular endothelia. The approximately 3.7-kb mRNA encodes a polypeptide of 1142 amino acids (calculated molecular weight 126.5 kD, pI 6.25), for which the name "symplekin" (from Greek sigma upsilon mu pi lambda epsilon kappa epsilon iota, nu, to tie together, to weave, to be intertwined) is proposed. However, both the mRNA and the protein can also be detected in a wide range of cell types that do not form tight junctions or are even completely devoid of any stable cell contacts. Careful analyses have revealed that the protein occurs in all these diverse cells in the nucleoplasm, and only in those cells forming tight junctions is it recruited, partly but specifically, to the plaque structure of the zonula occludens. We discuss symplekin as a representative of a group of dual residence proteins which occur and probably function in the nucleus as well as in the plaques exclusive for either tight junctions, adherens junctions, or desmosomes.
Article|
August 15 1996
Symplekin, a novel type of tight junction plaque protein.
B H Keon,
B H Keon
Division of Cell Biology, German Cancer Research Center, Heidelberg, Germany.
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S Schäfer,
S Schäfer
Division of Cell Biology, German Cancer Research Center, Heidelberg, Germany.
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C Kuhn,
C Kuhn
Division of Cell Biology, German Cancer Research Center, Heidelberg, Germany.
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C Grund,
C Grund
Division of Cell Biology, German Cancer Research Center, Heidelberg, Germany.
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W W Franke
W W Franke
Division of Cell Biology, German Cancer Research Center, Heidelberg, Germany.
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B H Keon
Division of Cell Biology, German Cancer Research Center, Heidelberg, Germany.
S Schäfer
Division of Cell Biology, German Cancer Research Center, Heidelberg, Germany.
C Kuhn
Division of Cell Biology, German Cancer Research Center, Heidelberg, Germany.
C Grund
Division of Cell Biology, German Cancer Research Center, Heidelberg, Germany.
W W Franke
Division of Cell Biology, German Cancer Research Center, Heidelberg, Germany.
Online ISSN: 1540-8140
Print ISSN: 0021-9525
J Cell Biol (1996) 134 (4): 1003–1018.
Citation
B H Keon, S Schäfer, C Kuhn, C Grund, W W Franke; Symplekin, a novel type of tight junction plaque protein.. J Cell Biol 15 August 1996; 134 (4): 1003–1018. doi: https://doi.org/10.1083/jcb.134.4.1003
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