Comparison of the proteins of two immunologically distinct intermediate-sized filaments by amino acid sequence analysis: desmin and vimentin.

Abstract

Although all intermediate-sized filaments (10-nm filaments) seem to show similar morphology and share a number of biochemical properties, different cell-and tissue-specific subclasses have been distinguished by immunological experiments and by differences in apparent molecular weights and isoelectric points of the major constituent proteins. In order to understand the degree of possible homology between these proteins, we have begun amino acid sequence analysis of the polypeptides. Here we characterize a large fragment of chicken gizzard and pig stomach desmin as well as the corresponding fragment from porcine eye lens vimentin. The fragments are situated at the carboxyl end and consist of 138-140 amino acid residues-i.e., some 28% ofthe corresponding polypeptide chains. The results show that the two immunologically distinct porcine-proteins are. different gene products. They show a related amino acid sequence but differ in 36% of the residues present in the carboxy-terminal part. In contrast the two desmins, although from species as diverse as chicken and pig, are more closely related and differ in less than 9% of the residues in the corresponding carboxy-terminal region. Thus tissue specificity overrides species divergence. These results are discussed in the light of previous immunological experiments. They lend further support to the hypothesis that intermediate filaments belong to a multigene family, which is expressed in line with certain rules of differentiation during embryogenesis.Intermediate-sized or 7-to 10-nm filaments form one of the three major components of the cytoskeleton. (5,6).In spite of the differences revealed by two-dimensional gel analysis and the lack of immunological crossreactivity experienced with many antibodies, the structural proteins of these filaments share several distinct properties. The filaments show a very similar ultrastructure and morphology and belong to the highly helical k-m-e-f-type ofproteins (see, for instance, ref. 7). In addition they are all insoluble in physiological buffers (for references see above) and, with the exception of certain neurofilament proteins, contain polypeptides of molecular weights in the range 45,000-68,000 (for references see refs. 1 and 2).In order to see whether different intermediate filament proteins are related in primary structure, we have started a comparative protein-chemical study based on partial amino acid sequence analysis. We chose stomach as the source of desmin, because it is generally the tissue of choice for the purification of this type of intermediate filament (1). In addition we have used eye lens fiber tissue as the source of an intermediate filament polypeptide distinct by apparent polypeptide molecular weight and isoelectric point. This protein has been immunologically and electrophoretically characterized (8) as related to the vimentin-type filaments typically expressed in fibroblasts and other mesenchymally derived cells as well as in most cultured cells (for references see refs. 1-4).Here we show that cleav...

Proteolysis of vimentin and desmin by the Ca2+-activated proteinase specific for these intermediate filament proteins.

“…Vimentin and desmin were phos-cyanobenzoic acid (NTCB) results in the cleavd in vitro with the protein kinase cata-age of the molecules at the site of cysteine nit from beef heart, as described in the residues (16 (13) is unknown. Nevertheless, Geisler and Weber have clearly shown that the 37,000-dalton fragment possesses the amino terminal of vimentin and desmin (11)(12)(13). We have, therefore, used this fact to determine whether the nucleic acid binding site is at the amino or the carboxy terminal of vimentin and desmin.…”

“…Most recently, it has been shown that there is ca. 70% amino acid sequence homology at the carboxy terminal between vimentin and desmin (11)(12)(13). In addition, both proteins bind to nucleic acids (38).…”

Characterization of Dopuin, a Polypeptide with Special Residue Distributions

“…The other peptide now obtained is a fragment of vimentin, a member of the intermediate filament in the cytoplasm of eukaryotic cells [21]. An eye lens vimentin segment has previously been described [22] but that was chemically produced in vitro, a C-terminal, 141-residue product. The gut vimentin fragment now purified is also derived from the C-terminal part, but involves only the last 37 residues.…”

Developmentally regulated cytokeratin gene in Xenopus laevis.

“…As in all other IF subunits examined, the homology is more pronounced in the central coiled-coil a-helical region. In this (15); porcine stomach desmin (PSD) (14); hamster desmin (HD) (44); hamster eye lens vimentin (HELV) (43); porcine eye lens vimentin (PELV) (14); and mouse glial fibrillary acidic protein (MGFAP) (27). region, XK70 is 53% homologous to XK81 and 49% homologous to UF29.…”