Microtubule assembly is dependent on a cluster of basic residues in alpha-tubulin

Biochemistry. 1986 Aug 12;25(16):4572-82. doi: 10.1021/bi00364a018.


Previous studies have shown that tubulin, a major protein component of the microtubule, is rendered assembly incompetent when a highly reactive lysine residue (HRL) in the alpha polypeptide of tubulin dimer is reductively methylated [cf. Sherman, G., Rosenberry, T. L., & Sternlicht, H. (1983) J. Biol. Chem. 258, 2148-2156]. In this study we demonstrate that the HRL in bovine brain tubulin is Lys-394, a residue proximal in the alpha-tubulin sequence to the highly negatively charged carboxy-terminus region (residues 412-450) previously implicated in assembly. pH studies were undertaken to probe the local environment of Lys-394. These studies indicated that Lys-394 reactivity toward HCHO is sensitive to the titration of a pKa 6.3 group presumed to be a histidine residue. This assignment is supported by our finding that histidine modification via diethyl pyrocarbonate strongly affects Lys-394 reactivity toward HCHO as well as microtubule assembly. We propose on the basis of secondary structure considerations and published sequence data for a variety of tubulins that Lys-394 is part of an evolutionarily conserved cluster of basic residues (effective charge: 2+ to 2.5+ at neutral pH) composed of Lys-394, His-393, and Arg-390, which is important for tubulin function and which renders Lys-394 reactive as a nucleophile.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Brain / metabolism
  • Cattle
  • Chickens
  • Cyanogen Bromide
  • Diethyl Pyrocarbonate / pharmacology
  • Histidine
  • Kinetics
  • Methylation
  • Microtubules / metabolism*
  • Microtubules / ultrastructure
  • Oxidation-Reduction
  • Peptide Fragments / isolation & purification
  • Rats
  • Schizosaccharomyces / metabolism
  • Species Specificity
  • Swine
  • Tubulin / metabolism*


  • Peptide Fragments
  • Tubulin
  • Histidine
  • Diethyl Pyrocarbonate
  • Cyanogen Bromide