A cell-counting factor regulating structure size in Dictyostelium

  1. Debra A. Brock and
  2. Richard H. Gomer
  1. Howard Hughes Medical Institute, Department of Biochemistry and Cell Biology MS-140, Rice University, Houston, Texas 77005-1892 USA

Abstract

Developing Dictyostelium cells form large aggregation streams that break up into groups of 0.2 × 105 to 1 × 105 cells. Each group then becomes a fruiting body.smlA cells oversecrete an unknown factor that causes aggregation streams to break up into groups of ∼5 × 103 cells and thus form very small fruiting bodies. We have purified the counting factor and find that it behaves as a complex of polypeptides with an effective molecular mass of 450 kD. One of the polypeptides is a 40-kD hydrophilic protein we have named countin. In transformants with a disrupted countin gene, there is no detectable secretion of counting factor, and the aggregation streams do not break up, resulting in huge (up to 2 × 105 cell) fruiting bodies.

Keywords

Footnotes

  • Corresponding author.

  • E-MAIL richard{at}bioc.rice.edu; FAX (713) 285-5154.

    • Received May 7, 1999.
    • Accepted June 4, 1999.
| Table of Contents

Life Science Alliance