Identification of a 51-kilodalton calmodulin binding protein that changes during estrogen-stimulated cell growth.
Calmodulin-binding proteins (CaMBPs) were analyzed during estrogen-stimulated growth in the human breast cancer cell line ZR-75-1. A variety of Ca2(+)-dependent and -independent CaMBPs were observed to be present in these cells. Calmodulin (CaM) binding to a 51-kilodalton protein was shown to be Ca2(+)-dependent. Moreover, binding to this protein was reduced in the estrogen-treated cells. This effect occurred early during estrogen-stimulated cell growth and was maintained during exponential growth in the presence of estrogen. 125I-labeled CaM overlay procedure of two-dimensional polyacrylamide gels reveals that this 51-kilodalton protein is composed of at least two distinct isoforms with different isoelectric points. Subcellular localization demonstrates that this protein resides exclusively in the microsomal fraction.
Research Centre, Laval University Medical Centre, Que., Canada.
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Laquerre
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Poulin
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Labrie
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JG
Chafouleas
D001943:Breast Neoplasms; D002118:Calcium / Q000494:pharmacology; D002147:Calmodulin / Q000378:metabolism; D002148:Calmodulin-Binding Proteins / Q000378:metabolism*; D002455:Cell Division / Q000187:drug effects; D015180:Electrophoresis, Gel, Two-Dimensional; D004958:Estradiol / Q000494:pharmacology*; D006801:Humans; D007526:Isoelectric Point; D008861:Microsomes / Q000378:metabolism; D008970:Molecular Weight; D014407:Tumor Cells, Cultured
D002147:Calmodulin; D002148:Calmodulin-Binding Proteins; D004958:Estradiol; D002118:Calcium