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cDNA cloning and gene mapping of a candidate human cell cycle checkpoint protein
K A Cimprich1, T B Shin, C T Keith
1Howard Hughes Medical Institute, Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138, USA.
Abstract:
A family of proteins involved in cell cycle progression, DNA recombination, and the detection of DNA damage has been recently identified. One of the members of this family, human ATM, is defective in the cells of patients with ataxia telangiectasia and is involved in detection and response of cells to damaged DNA. Other members include Mei-41 (Drosophila melanogaster), Mec1p (Saccharomyces cerevisiae), and Rad3 (Schizosaccharomyces pombe), which are required for the S and G2/M checkpoints, as well as FRAP (Homo sapiens) and Torl/2p (S. cerevisiae), which are involved in a rapamycin-sensitive pathway leading to G1 cell cycle progression. We report here the cloning of a human cDNA encoding a protein with significant homology to members of this family. Three overlapping clones isolated from a Jurkat T-cell cDNA library revealed a 7.9-kb open reading frame encoding a protein that we have named FRP1 (FRAP-related protein) with 2644 amino acids and a predicted molecular mass of 301 kDa. Using fluorescence in situ hybridization and a full-length cDNA FRP1 clone, the FRP1 gene has been mapped to the chromosomal locus 3q22-q24. FRP1 is most closely related to three of the PIK-related kinase family members involved in checkpoint function--Mei-41, Mec1p, and Rad3--and as such may be the functional human counterpart of these proteins.
Insights
Researchers identified FRP1, a novel human protein homologous to PIK-related kinases involved in DNA damage response and cell cycle control. This discovery offers insights into cell cycle regulation and DNA repair mechanisms.
Area of Science:
- Molecular Biology
- Cell Biology
- Genetics
Background:
- A family of proteins regulating cell cycle, DNA recombination, and DNA damage detection has been identified.
- Human ATM protein, defective in ataxia telangiectasia, is crucial for DNA damage response.
- Related proteins in yeast and flies regulate cell cycle checkpoints and progression.
Purpose of the Study:
- To clone and characterize a novel human protein homologous to known cell cycle and DNA damage response proteins.
- To identify the human counterpart of Mei-41, Mec1p, and Rad3 involved in checkpoint functions.
Main Methods:
- Cloning of human cDNA from a Jurkat T-cell library.
- Sequence analysis to identify open reading frame and predict protein characteristics.
- Fluorescence in situ hybridization (FISH) for gene mapping.
Main Results:
- A 7.9-kb open reading frame encoding a 301 kDa protein, named FRP1 (FRAP-related protein), was identified.
- The FRP1 gene was mapped to human chromosomal locus 3q22-q24.
- FRP1 exhibits significant homology to Mei-41, Mec1p, and Rad3, suggesting a role in checkpoint function.
Conclusions:
- FRP1 is a novel human protein belonging to the PIK-related kinase family.
- FRP1 may function as the human counterpart to yeast and fly checkpoint proteins.
- The discovery of FRP1 provides new avenues for understanding DNA damage response and cell cycle regulation in humans.