The 68 kDa calmodulin-binding protein is tightly associated with the multiprotein DNA polymerase alpha-primase complex in HeLa cells.
Calcium and its receptor protein calmodulin function in the regulation of proliferation of mammalian cells. A 68 kDa calmodulin-specific binding protein was shown previously to be associated with growth factor-dependent progression of a variety of mammalian cells from G1 to S phase and to stimulate DNA synthesis in permeabilized hematopoietic progenitor cells. In this report we show that the 68 kDa calmodulin-specific binding protein in HeLa cells is tightly associated with the DNA polymerase alpha-primase component of the 21S complex of enzymes for DNA synthesis. The 68 kDa calmodulin-binding protein and the DNA polymerase alpha-primase complex cofractionate during Q-Sepharose chromatography to isolate the 21S enzyme complex, native and denatured DNA-cellulose to dissociate the 21S complex, and DEAE-Bio-Gel chromatography to isolate the multiprotein DNA polymerase alpha-primase complex. The 68 kDa calmodulin-specific binding protein and DNA polymerase alpha also bind and coelute during affinity chromatography on calmodulin-agarose. They also coprecipitate with C10-agarose-linked monoclonal antibody SJK 132-20 to human DNA polymerase alpha. The tight association of the 68 kDa calmodulin-binding protein to the DNA polymerase alpha-primase complex supports a function for this protein in the regulation of DNA synthesis in vivo.
Cao
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QP
Cancer Center, University of Massachusetts Medical Center, Worcester 01655.
McGrath
C A
CA
Baril
E F
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Quesenberry
P J
PJ
Reddy
G P
GP
D002147:Calmodulin; D002148:Calmodulin-Binding Proteins / Q000737:chemistry* / Q000302:isolation & purification; D002453:Cell Cycle; D002458:Cell Fractionation; D002846:Chromatography, Affinity; D002852:Chromatography, Ion Exchange; D019915:DNA Primase; D004261:DNA Replication; D004591:Electrophoresis, Polyacrylamide Gel; D006367:HeLa Cells; D006801:Humans; D008970:Molecular Weight; D012316:RNA Nucleotidyltransferases / Q000737:chemistry* / Q000302:isolation & purification
D002147:Calmodulin; D002148:Calmodulin-Binding Proteins; D019915:DNA Primase; D012316:RNA Nucleotidyltransferases