A 50 kilodalton protein associated with raf and pp60(v-src) protein kinases is a mammalian homolog of the cell cycle control protein cdc37.
Several oncogenic protein kinases including c-raf-1 and pp60(v-src) are known to directly interact with the 90 kDa heat shock protein (hsp90)/p50 complexes. Using a monoclonal antibody to detect p50 during a purification scheme, p50 was purified to homogeneity. Internal amino acid sequence information was obtained and used to clone a partial cDNA. Comparison of the p50 sequence to other cloned proteins revealed 89% homology with a glycosaminoglycan-binding protein and 54% homology with Drosophila cell cycle control protein (cdc) 37. Monoclonal and polyclonal antibodies were produced against a cleaved fusion protein that recognizes p50 with a high level of specificity. These antibodies recognize the 50 kDa protein present in c-raf-1 and pp60(v-src) complexes. No other proteins were recognized with these antibodies suggesting that p50 is a unique protein. Immunocytochemical visualization of p50 in NIH 3T3 cells indicates a primarily cytoplasmic localization around the nuclear membrane. A survey of p50 expression in murine tissues on a protein blot revealed the following relative levels of expression; thymus > spleen > brain > heart > kidney > liver > lung > skeletal muscle. These results link studies demonstrating complexation of certain kinases with hsp90/p50 in mammalian cells and a number of reports in yeast and Drosophila, demonstrating the importance of cdc37 in cell cycle and kinase function.
Perdew
G H
GH
Department of Veterinary Science, The Pennsylvania State University, University Park 16802, USA.
Wiegand
H
H
Vanden Heuvel
J P
JP
Mitchell
C
C
Singh
S S
SS
D016475:3T3 Cells; D000595:Amino Acid Sequence; D000818:Animals; D000911:Antibodies, Monoclonal; D015153:Blotting, Western; D018797:Cell Cycle Proteins / Q000737:chemistry*; D002851:Chromatography, High Pressure Liquid; D003001:Cloning, Molecular; D004330:Drosophila; D029721:Drosophila Proteins; D019084:Fluorescent Antibody Technique, Indirect; D006360:Heat-Shock Proteins / Q000737:chemistry* / Q000302:isolation & purification; D007075:Immunoglobulin M; D051379:Mice; D018832:Molecular Chaperones; D008969:Molecular Sequence Data; D008970:Molecular Weight; D015688:Oncogene Protein pp60(v-src) / Q000737:chemistry*; D016133:Polymerase Chain Reaction; D017346:Protein Serine-Threonine Kinases / Q000737:chemistry*; D011518:Proto-Oncogene Proteins / Q000737:chemistry*; D019908:Proto-Oncogene Proteins c-raf
D000911:Antibodies, Monoclonal; C088085:Cdc37 protein, Drosophila; C513271:Cdc37 protein, mouse; D018797:Cell Cycle Proteins; D029721:Drosophila Proteins; D006360:Heat-Shock Proteins; D007075:Immunoglobulin M; D018832:Molecular Chaperones; D011518:Proto-Oncogene Proteins; D015688:Oncogene Protein pp60(v-src); D017346:Protein Serine-Threonine Kinases; D019908:Proto-Oncogene Proteins c-raf