Molecular structure of a proteolytic fragment of TLP20

Hazel M. Holden, Gary Wesenberg, Deborah A. Raynes, David J. Hartshorne, Vincent Guerriero, Ivan Rayment

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Abstract

Myosin light-chain kinase is responsible for the phosphorylation of myosin in smooth muscle cells. In some tissue types, the C-terminal portion of this large enzyme is expressed as an independent protein and has been given the name telokin. Recently, an antibody directed against telokin was found to interact with a protein derived from the baculovirus Autographa californica nuclear polyhedrosis virus. This protein was biochemically characterized and given the name TLP20 for telokin-like protein of 20 000 molecular weight. The amino-acid sequence of TLP20 was determined on the basis of a cDNA clone and subsequent alignment searches failed to reveal any homology to telokin or to other known proteins. The three-dimensional structure of a proteolytic portion of TLP20 is reported here. Crystals employed in the investigation were grown from ammonium sulfate solutions at pH 6.0 and belonged to the space group P213 with unit-cell dimensions of a = b = c = 76.3 Å and one molecule per asymmetric unit. The structure was determined by multiple isomorphous replacement with three heavy-atom derivatives. Least-squares refinement of the model reduced the crystallographic R factor to 18.1% for all measured X-ray data from 30.0 to 2.2 Å. The overall fold of the molecule may be described as a seven-stranded antiparallel β-barrel flanked on the bottom by two additional β-strands and on top by an α-helix. Quite surprisingly, the three-dimensional structure of this β-barrel is not similar to telokin or to any other known protein.

Original languageEnglish (US)
Pages (from-to)1153-1160
Number of pages8
JournalActa Crystallographica Section D: Biological Crystallography
Volume52
Issue number6
DOIs
Publication statusPublished - 1996

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ASJC Scopus subject areas

  • Clinical Biochemistry
  • Biochemistry, Genetics and Molecular Biology(all)
  • Biochemistry
  • Biophysics
  • Condensed Matter Physics
  • Structural Biology

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