Control of microtubule assembly-disassembly by calcium-dependent regulator protein.

Journal Article (Journal Article)

The Ca2+-dependent regulator (CDR) protein of cyclic nucleotide phosphodiesterase is a low molecular weight, acidic, Ca2+-binding protein which has been implicated in a number of Ca2+-dependent enzymatic functions. Indirect immunofluorescence has revealed that CDR is specifically associated with the chromosome-to-pole region of the mitotic apparatus during metaphase-anaphase in a pattern distinctly different from that of similar cultured cells stained with antitubulin. This characteristic localization in the mitotic half-spindle suggested a role for CDR in the control of microtubule assembly-disassembly during mitosis. Thus, CDR was examined for its effects on microtubule polymerization in vitro. It was determined that stoichiometric concentrations of CDR and a homologous Ca2+-binding protein, skeletal muscle troponin C, both inhibited and reversed microtubule assembly in a Ca2+-dependent manner. CDR-dependent inhibition of in vitro microtubule assembly occurred at physiological Ca2+ concentrations (approximately 10 micron) that, in the absence of CDR, caused only a slight reduction in polymerization. At Ca2+ concentrations in the low physiological range (less than 1 micron), no inhibition was observed. These biochemical results, together with the immunofluorescent localization of CDR in the mitotic half-spindle, provide evidence that Ca2+ is an endogenous regulator of microtubule disassembly through the activity of CDR.

Full Text

Duke Authors

Cited Authors

  • Marcum, JM; Dedman, JR; Brinkley, BR; Means, AR

Published Date

  • August 1, 1978

Published In

Volume / Issue

  • 75 / 8

Start / End Page

  • 3771 - 3775

PubMed ID

  • 211505

Pubmed Central ID

  • PMC392868

International Standard Serial Number (ISSN)

  • 0027-8424

Digital Object Identifier (DOI)

  • 10.1073/pnas.75.8.3771


  • eng

Conference Location

  • United States