Molecular evolution/Intermediate filament proteins

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Cultured mouse cells stained to show keratin filaments.

Welcome to the Wikiversity learning project for exploration of the molecular evolution of intermediate filament proteins.

The intermediate filament proteins are a major family of cytoskeletal proteins. Most eukaryotic organisms have genes that code for intermediate filament proteins[1]. As more genomes are sequenced, an increasing complete understanding of the evolution of protein families becomes possible. Are intermediate filament proteins related to any proteins of prokayotic organisms? At what points during the evolution of eukaryotes did the various subtypes of intermediate filament proteins arise? What new biological functions and specializations were facilitated by the evolution of the members of this multigene family?

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Explore the Conserved Domain Database online resources from the National Library of Medicine[2].

A Conserved Domain relatedness tree exploring tool is available for Windows.

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Keratins[edit]

Keratin 18 is one of the major keratin proteins of human epithelial cells. There are two major families of keratins, type I and type II. Keratin 18 is type I and often forms intermediate filaments by combining with a type II partner, keratin 8. Keratin filaments containing keratins 8 and 18 are found in the earliest epithelial cells of mammalian embryos [3]. The functional role of early embryo keratin 8 has been investigated in transgenic mice lacking keratin 8 [4]. Mice lacking keratin 8 have disrupted placental barrier function.

Lamins[edit]

Lamins are intermediate filament family proteins found in the nuclei of metazoans. It has been suggested that during mitosis lamin B forms a matrix for assembly of microtubules[5].

References[edit]

  1. Intermediate Filaments, in Chapter 19 of Molecular Cell Biology Fourth Edition by Harvey Lodish, Arnold Berk, Lawrence Zipursky, Paul Matsudaira, David Baltimore and James Darnell (2000) ISBN 0-7167-3706-X.
  2. "CDD: a Conserved Domain Database for protein classification" by Aron Marchler-Bauer, et al in Nucleic Acids Research (2005) January 1; 33(Database Issue): D192–D196.
  3. "Comparison of the gene expression profile of undifferentiated human embryonic stem cell lines and differentiating embryoid bodies" by Bhaskar Bhattacharya, Jingli Cai, Youngquan Luo, Takumi Miura, Josef Mejido, Sandii N. Brimble, Xianmin Zeng, Thomas C. Schulz, Mahendra S. Rao and Raj K. Puri in BMC Developmental Biology (2005) 5: 22.
  4. "Keratin 8 protection of placental barrier function" by Daniel Jaquemar, Sergey Kupriyanov, Miriam Wankell1, Jacqueline Avis, Kurt Benirschke, Hélène Baribault and Robert G. Oshima in Journal of Cell Biology, Volume 161, pages 749-756.
  5. "A Mitotic Lamin B Matrix Induced by RanGTP Required for Spindle Assembly" by Ming-Ying Tsai, Shusheng Wang, Jill M. Heidinger, Dale K. Shumaker, Stephen A. Adam, Robert D. Goldman and Yixian Zheng in Science (2006) Volume 311, pages 1887 - 1893.

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