ISSN:
1615-6102
Keywords:
Kinesin-like motor
;
Mammalian cell cycle
;
Centrosomes
;
Mitotic spindles
;
Nuclear antigen
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Notes:
Summary A 69 kDa protein present in the interphase centrosome and mitotic spindle/pole was identified with the CHO2 monoclonal antibodies raised against mitotic spindles isolated from Chinese hamster ovary (CHO) cells. Isolation and characterization of antigen-specific cDNAs and recombinant proteins demonstrated that the protein is a minus-end-directed microtubule motor with the motor domain located at the C terminus. Affinity-purified polyclonal antibodies prepared to bacterially expressed fusion proteins revealed the presence of the antigen in interphase nuclei, and the degree of nuclear immunostaining intensity varied among cells at different cell cycle stages. In order to examine the change of antigen expression during the cell cycle, we prepared synchronized populations of CHO cells, double stained with CHO2 and PCNA (proliferating cell nuclear antigen) antibodies, and quantitated the amounts of nuclear fluorescence using the MetaMorpho image analysis software package. Cells right after cell division contained nuclei with the lowest level of CHO2 immunofluorescence. The immunofluorescence intensity progressively increases through G1 to S, reaching a maximum level by the end of G2. The antibody uniformly stained the entire nuclear region, and the total amount of fluorescence detected in G2 cells was greater than three times that of G1 cells. Cell cycle dependent accumulation of the CHO2 antigen was further confirmed by immunoblot analysis of the protein included in whole cell extracts and nuclei isolated from synchronized CHO cells. Northern blot analysis showed that, although the CHO2-transcript accumulated during later stages of the cell cycle, its abundance declined through G1 to S, and was lowest in cells at the early S phase. The difference in the expression pattern of the antigen protein and its transcript may suggest the presence of multiple mechanisms controlling the level of CHO2 antigen during the course of the cell cycle.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF01281312
Permalink
