title: A cell-counting factor regulating structure size in Dictyostelium.
abstract: Developing Dictyostelium cells form large aggregation streams that break up into groups of 0.2 x 10(5) to 1 x 10(5) cells. Each group then becomes a fruiting body. smlA cells oversecrete an unknown factor that causes aggregation streams to break up into groups of approximately 5 x 10(3) 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 counting. In transformants with a disrupted counting gene, there is no detectable secretion of counting factor, and the aggregation streams do not break up, resulting in huge (up to 2 x 10(5) cell) fruiting bodies.
authors.affiliation: Howard Hughes Medical Institute, Department of Biochemistry and Cell Biology MS-140, Rice University, Houston, Texas 77005-1892, USA.
authors.forename: D A
authors.initials: DA
authors.lastname: Brock
authors.forename: R H
authors.initials: RH
authors.lastname: Gomer
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002449:Cell Aggregation; D002452:Cell Count; D003001:Cloning, Molecular; D017077:Culture Media, Conditioned; D004023:Dictyostelium / Q000166:cytology* / Q000235:genetics / Q000254:growth & development*; D008969:Molecular Sequence Data; D008970:Molecular Weight; D009154:Mutation; D010641:Phenotype; D021382:Protein Sorting Signals / Q000235:genetics; D015800:Protozoan Proteins / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D017421:Sequence Analysis; D015398:Signal Transduction
chemical_list: D017077:Culture Media, Conditioned; D021382:Protein Sorting Signals; D015800:Protozoan Proteins; D012333:RNA, Messenger; C101537:SmlA protein, Dictyostelium discoideum; C120918:countin protein, Dictyostelium discoideum