title: Dictyostelium nucleomorphin is a member of the BRCT-domain family of cell cycle checkpoint proteins.
abstract: A search of the Dictyostelium genome project database (http://dictybase.org/db/cgi-bin/blast.pl) with nucleomorphin, a protein that regulates the nuclear number, predicted it to be encoded by a larger gene containing a putative breast cancer carboxy-terminus domain (BRCT). Using RT-PCR, Northern and Western blotting we have identified a differentially expressed, 2318 bp cDNA encoding a protein isoform of Dictyostelium NumA with an apparent molecular weight of 70 kDa that we have called NumB. It contains a single amino-terminal BRCT-domain spanning residues 125-201. Starvation of shaking cultures reduces NumA expression by approximately 88+/-5.6%, whereas NumB expression increases approximately 35+/-3.5% from vegetative levels. NumC, a third isoform that is also expressed during development but not growth, remains to be characterized. These findings suggest NumB may be a member of the BRCT-domain containing cell cycle checkpoint proteins.
authors.affiliation: Department of Biology, University of Toronto at Mississauga, 3359 Mississauga Rd., Rm. 3030, Mississauga, ON, Canada L5L 1C6.
authors.forename: Michael A
authors.initials: MA
authors.lastname: Myre
authors.forename: Danton H
authors.initials: DH
authors.lastname: O'Day
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D019313:BRCA1 Protein / Q000737:chemistry; D001483:Base Sequence; D015152:Blotting, Northern; D015153:Blotting, Western; D018797:Cell Cycle Proteins / Q000737:chemistry*; D002467:Cell Nucleus / Q000378:metabolism*; D004023:Dictyostelium / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D009687:Nuclear Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D020033:Protein Isoforms; D017434:Protein Structure, Tertiary; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017386:Sequence Homology, Amino Acid
chemical_list: D019313:BRCA1 Protein; D018797:Cell Cycle Proteins; D009687:Nuclear Proteins; D020033:Protein Isoforms