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Published August 1, 1979 | public
Journal Article Open

Coexistence of desmin and the fibroblastic intermediate filament subunit in muscle and nonmuscle cells: Identification and comparative peptide analysis


Extraction of chicken embryo fibroblasts (CEF) or baby hamster kidney (BHK) cells with 1% Triton X-100 and 0.6 M KCl leaves an insoluble cytoskeletal residue composed primarily of the 52,000 Mr subunit of intermediate filaments (F-IFP). In addition, CEF cytoskeletons exhibit a minor component with Mr of 50,000, identified as α-desmin, one of the two major isoelectric variants of the intermediate filament subunit from smooth muscle. BHK cytoskeletons contain the 50,000 Mr mammalian desmin variant. Cytoskeletons prepared from chicken embryonic myotubes contain F-IFP and both α- and β-desmin. These data suggest that two distinct 10-nm filament subunits coexist in a single cell. One-dimensional peptide analysis of F-IFP and desmin from avian and mammalian cells reveals significant interspecies homology, as well as homology between F-IFP and desmin from the same species. Peptide analyses of 32P-labeled intermediate filament subunits suggest that there is considerable similarity in the phosphorylation sites of these proteins. These results indicate that F-IFP and desmin might be evolutionally related.

Additional Information

© 1979 by the National Academy of Sciences. Communicated by James F. Bonner, April 16, 1979. We thank Dr. C. O'Connor for her valuable assistance with the phosphopeptide analysis and D.R. Balzer, I. Lielausis, and Jean Edens for their technical assistance. We thank Dr. C. O'Connor and B.L. Granger for their many valuable comments during the preparation of this manuscript. This work was supported by a grant from the National Institutes of Health (PHS GM 06965-19) and by a grant from the Muscular Dystrophy Association of America. D.L.G. was also supported by a National Science Foundation Graduate Fellowship. The publication costs of this article were defrayed in part by page charge payment. This article must therefore be hereby marked "advertisement" in accordance with 18 U.S.C. §1734 solely to indicate this fact.


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August 22, 2023
October 16, 2023