Mammalian checkpoint proteins polypeptides and encoding sequences thereof

Abstract

The present invention relates to the isolation of gene sequences encoding mammalian cell cycle checkpoints, as well as the expression of the encoded proteins using recombinant DNA technology. The expressed proteins are used to generate specific antibodies and to inhibit the growth of cells. The human checkpoint gene sequences are used as a probe for a portion of the chromosome associated with tumors and other malignancies, as well as growth and/or development deficiencies.

1. A purified human protein, wherein the protein is a polypeptide having checkpoint kinase activity and encoded by the nucleotide sequence of  SEQ ID NO: 3. 
     
     
       2. A purified human protein comprising the amino acid sequence set forth in  having checkpoint kinase activity, wherein the protein comprises SEQ ID NO: 1. 
     
     
       3. A fusion protein comprising a portion of  at least 15 sequential amino acids of the  a carboxy-terminus of the CHK1 protein of  claim 2 ,  sequence of SEQ ID NO: 1  and a non-CHk 1  Chk1  protein sequence . 
     
     
       4. The fusion protein of  claim 3 , wherein said non-Chk1 protein sequence comprises  is combined with an affinity tag for purification of the fusion protein. 
     
     
       5. The fusion protein of  claim 4 , wherein said affinity tag comprises  is a histidine tag. 
     
     
       6. A purified Chk1  protein encoded by the nucleotide sequence  of  claim 5 . 
     
     
       7. The fusion protein of either  claim 3  or  claim 6 , wherein the non- Chk 1  protein is glutathione S-I transferase.