Dataset Information

Primary structure of tektin A1: comparison with intermediate-filament proteins and a model for its association with tubulin.

ABSTRACT: Tektins are proteins that form filamentous polymers in the walls of ciliary and flagellar microtubules and that have biochemical and immunological properties similar to those of intermediate-filament proteins. We report here the sequence of a cDNA for tektin A1, one of the main tektins from Strongylocentrotus purpuratus sea urchin embryos. By hybridization analysis, tektin A mRNA appears maximally at ciliogenesis. The predicted structure of tektin A1 (M(r) 52,955) is a series of alpha-helical rod segments separated by nonhelical linkers. The two halves of the rod appear homologous and are probably related by gene duplication. Comparison of tektin A1 with intermediate-filament proteins, including nuclear lamins, reveals a low amino acid homology but similar molecular motif, i.e., pattern of helical and nonhelical domains. This study indicates that tektins are unique proteins but may be evolutionarily related to intermediate-filament proteins, and suggests a structural basis for the interaction of tektins and tubulin in microtubules.

SUBMITTER: Norrander JM

PROVIDER: S-EPMC49961 | biostudies-other | 1992 Sep

REPOSITORIES: biostudies-other

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Primary structure of tektin A1: comparison with intermediate-filament proteins and a model for its association with tubulin.

Norrander J M JM Amos L A LA Linck R W RW

Proceedings of the National Academy of Sciences of the United States of America 19920901 18

Tektins are proteins that form filamentous polymers in the walls of ciliary and flagellar microtubules and that have biochemical and immunological properties similar to those of intermediate-filament proteins. We report here the sequence of a cDNA for tektin A1, one of the main tektins from Strongylocentrotus purpuratus sea urchin embryos. By hybridization analysis, tektin A mRNA appears maximally at ciliogenesis. The predicted structure of tektin A1 (M(r) 52,955) is a series of alpha-helical ro ...[more]

PMID: 1528862

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Project description:Intermediate filament (IF) proteins assemble into highly flexible filaments that organize into complex cytoplasmic networks: keratins in all types of epithelia, vimentin in endothelia, and desmin in muscle. Since IF elongation proceeds via end-to-end annealing of unit-length filaments and successively of progressively growing filaments, it is important to know how their remarkable flexibility, i.e., their persistence length lp, influences the assembly kinetics. In fact, their lp ranges between 0.3 μm (keratin K8/K18) and 1.0 μm (vimentin and desmin), and thus is orders of magnitude lower than that of microtubules and F-actin. Here, we present a unique mathematical model, which implements the semiflexible nature of the three IF types based on published semiflexible polymers theories and depends on a single free parameter k0. Calibrating this model to filament mean length dynamics of the three proteins, we demonstrate that the persistence length is indeed essential to accurately describe their assembly kinetics. Furthermore, we reveal that the difference in flexibility alone does not explain the significantly faster assembly rate of keratin filaments compared with that of vimentin. Likewise, desmin assembles approximately six times faster than vimentin, even though both their filaments exhibit the same lp value. These data strongly indicate that differences in their individual amino acid sequences significantly impact the assembly rates. Nevertheless, using a single k0 value for each of these three key representatives of the IF protein family, our advanced model does accurately describe the length distribution and mean length dynamics and provides effective filament assembly rates. It thus provides a tool for future investigations on the impact of posttranslational modifications or amino acid changes of IF proteins on assembly kinetics. This is an important issue, as the discovery of mutations in IF genes causing severe human disease, particularly for desmin and keratins, is steadily increasing.

Dataset Information

Primary structure of tektin A1: comparison with intermediate-filament proteins and a model for its association with tubulin.

Publications

Primary structure of tektin A1: comparison with intermediate-filament proteins and a model for its association with tubulin.

Similar Datasets

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