Cleavage of cyclin A by cyclin B translated in rabbit RL.
(A) Cyclin B(RL) induces efficient cleavage of cyclin
A(CΔ114). GST-cyclin A(CΔ114) was mixed with unprogrammed RL (lanes
2 and 3) or cyclin B(RL) (lane 4). The reactions were incubated at
37°C and stopped with SDS-sample buffer at the indicated time. The
proteins were analyzed by SDS/PAGE and Coomassie blue
staining. Molecular size standards (lane 1) in kDa are indicated on the
left. The positions of GST-cyclin A(CΔ114) and the cleaved form of
cyclin A (*) are indicated on the right. (B)
Cleavage of cyclin A expressed in mammalian cells into two fragments by
cyclin B(RL). FLAG-cyclin A was transiently transfected into HtTA1
cells. Cell extracts were prepared and the expressed cyclin A were
immunoprecipitated with anti-FLAG antibodies. The immunoprecipitates
were incubated with unprogrammed RL or cyclin B(RL) as indicated. The
samples were applied onto 12.5% SDS/PAGE (top two panels) or
Tricine gel (bottom two panels), and subjected to immunoblotting with
anti-FLAG mAb M2, anti-cyclin A monoclonal E23, or M2 and E23 together
as indicated. In this paper, the N-terminal fragment of cyclin A is
denoted with “*”, and the C-terminal fragment is denoted
with “**” (see main text).