Abstract
The 3'-ends of the β-tubulin cDNA were amplified by 3'RACE and were grouped into five different isotypes, NTB1-5.
Individual isotype RNA levels during the progress of the cell cycle were quantitated by real time RT-PCR. The NTB1 mRNA kept the highest level throughout the cell cycle. NTB2 and 3 mRNAs were present at nearly equivalent levels, but the amplitude of variation of NTB2 was much higher than NTB3 mRNA. NTB4 and 5 isotypes were expressed at low levels. All of the five isotype RNAs decreased during or after mitosis.
The polyA attachment sites of NTB1-3 were found to be heterogeneous, giving different length of 3'-UTR for the same gene transcripts. The shortest mRNA of NTB2 and 3 existed around G2 to M phases.
β-tubulin isoforms in BY2 cells were separated into at least five spots on 2-D PAGE. Identification of each spot is now under investigation.
