Identification of a 52-kD calmodulin-binding protein associated with the mitotic spindle apparatus in mammalian cells.
A pool of 10 calmodulin-binding proteins (CBPs) was isolated from Chinese hamster ovary (CHO) cells via calmodulin (CaM)-Sepharose affinity chromatography. One of these ten isolated CBPs with a molecular mass of 52 kD was also found to be present in isolated CHO cell mitotic spindles. Affinity-purified antibodies generated against this pool of isolated CBPs recognize a single 52-kD protein in isolated CHO cell mitotic spindles by immunoblot analysis. Immunofluorescence examination of CHO, 3T3, NRK, PTK-2, and HeLa cells resulted in a distinct pattern of mitotic spindle fluorescence. The localization pattern of this 52-kD CBP directly parallels that of CaM in the spindle apparatus throughout the various stages of mitosis. Interestingly, there was no association of this 52-kD CBP with cytoplasmic microtubules. As is the case with CaM, the localization pattern of the 52-kD CBP in interphase cells is diffuse within the cytoplasm and is not associated with any discrete, cellular structures. This 52-kD CBP appears to represent the first mitotic spindle-specific calmodulin-binding protein identified and represents an initial step toward the ultimate determination of CaM function in the mitotic spindle apparatus.
D000818:Animals; D002147:Calmodulin / Q000378:metabolism*; D002148:Calmodulin-Binding Proteins / Q000378:metabolism*; D002460:Cell Line; D006224:Cricetinae; D005455:Fluorescent Antibody Technique; D008938:Mitosis; D008970:Molecular Weight; D008941:Spindle Apparatus / Q000378:metabolism*
D002147:Calmodulin; D002148:Calmodulin-Binding Proteins