Abstract
Polypyrimidine tract-binding protein (PTB) belongs to a member of heterogeneous nuclear ribonucleoproteins (hnRNPs). In animals, PTB proteins are known to play multiple roles in splicing, intracellular sorting and nucleocytoplasmic transport of mRNA, and be involved in differentiation and development. In Arabidopsis, there are two PTB genes (AtPTB1 and 2), and they have been shown to express mainly in mature pollen grains, stigma and funiculus but not in developing embryos. Null mutants (ptb1-/- and ptb2-/-) showed no phenotype. However, double mutant (ptb1-/-ptb2-/-) could not be obtained, indicating that PTBs are essential for reproduction, development or growth of Arabidopsis. Approximately 1/3 pollen grains of ptb1-/-ptb2+/- showed developmental defect, and germination efficiency of pollen grains was reduced in ptb1-/-ptb2+/- and ptb1+/-ptb2-/-. Analyses for monitoring developmental defect in ptb1-/-ptb2+/- pollen grains using qrt, and for intracellular localization of AtPTB1,2-GFP fusion proteins are under investigation.
