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.
Laquerre
S
S
Research Centre, Laval University Medical Centre, Que., Canada.
Poulin
R
R
Labrie
F
F
Chafouleas
J G
JG
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