title: Cloning and sequence of the human nuclear protein cyclin: homology with DNA-binding proteins.
abstract: A full-length cDNA clone for the human nuclear protein cyclin has been isolated by using polyclonal antibodies and sequenced. The sequence predicts a protein of 261 amino acids (Mr 29,261) with a high content of acidic (41, aspartic and glutamic acids) versus basic (24, lysine and arginine) amino acids. The identity of the cDNA clone was confirmed by in vitro hybrid-arrested translation of cyclin mRNA. Blot-hybridization analysis of mouse 3T3 and human MOLT-4 cell RNA revealed a mRNA species of approximately the same size as the cDNA insert. Expression of cyclin mRNA was undetectable or very low in quiescent cells, increasing after 8-10 hr of serum stimulation. Inhibition of DNA synthesis by hydroxyurea in serum-stimulated cells did not affect the increase in cyclin mRNA but inhibited 90% the expression of H3 mRNA. These results suggest that expression of cyclin and histone mRNAs are controlled by different mechanisms. A region of the cyclin sequence shows a significant homology with the putative DNA binding site of several proteins, specially with the transcriptional-regulator cAMP-binding protein of Escherichia coli, suggesting that cyclin could play a similar role in eukaryotic cells.
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001790:Blood Physiological Phenomena; D003001:Cloning, Molecular; D004247:DNA / Q000032:analysis / Q000096:biosynthesis; D004268:DNA-Binding Proteins / Q000032:analysis*; D006801:Humans; D051379:Mice; D009698:Nucleoproteins / Q000032:analysis / Q000235:genetics* / Q000276:immunology; D018809:Proliferating Cell Nuclear Antigen; D014176:Protein Biosynthesis; D012333:RNA, Messenger / Q000096:biosynthesis
chemical_list: D004268:DNA-Binding Proteins; D009698:Nucleoproteins; D018809:Proliferating Cell Nuclear Antigen; D012333:RNA, Messenger; D004247:DNA